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<div id="org-div-home-and-up">
<a accesskey="h" href=""> UP </a>
|
<a accesskey="H" href="index.html"> HOME </a>
</div><div id="content">
<h1 class="title">Electrons</h1>
<div id="table-of-contents">
<h2>Table of Contents</h2>
<div id="text-table-of-contents">
<ul>
<li><a href="#org1c1356c">1. Context</a>
<ul>
<li><a href="#org15fab56">1.1. Data structure</a></li>
<li><a href="#org6bb5fa1">1.2. Initialization functions</a></li>
<li><a href="#org148643a">1.3. Access functions</a>
<ul>
<li><a href="#orgd3cec20">1.3.1. Number of electrons</a></li>
<li><a href="#orgc0c2b28">1.3.2. Number of walkers</a></li>
<li><a href="#orgd35c18c">1.3.3. Electron coordinates</a></li>
</ul>
</li>
<li><a href="#org1b334dc">1.4. Test</a></li>
</ul>
</li>
<li><a href="#orgdc6fbed">2. Computation</a>
<ul>
<li><a href="#org27ac20c">2.1. Electron-electron distances</a>
<ul>
<li><a href="#org0579ccb">2.1.1. Get</a></li>
<li><a href="#orga29444d">2.1.2. Compute</a></li>
<li><a href="#orgbac7d2b">2.1.3. Test</a></li>
</ul>
</li>
<li><a href="#org29a7e21">2.2. Electron-electron potential</a>
<ul>
<li><a href="#orga611bf8">2.2.1. Get</a></li>
<li><a href="#org3f78270">2.2.2. Compute</a></li>
<li><a href="#orga2c1d7d">2.2.3. Test</a></li>
</ul>
</li>
<li><a href="#orga7496f3">2.3. Electron-nucleus distances</a>
<ul>
<li><a href="#org0614625">2.3.1. Get</a></li>
<li><a href="#orgc1c1fbd">2.3.2. Compute</a></li>
<li><a href="#orgdd427ab">2.3.3. Test</a></li>
</ul>
</li>
<li><a href="#org8d56cf2">2.4. Electron-nucleus potential</a>
<ul>
<li><a href="#orgb431d98">2.4.1. Get</a></li>
<li><a href="#orgb0284b1">2.4.2. Compute</a></li>
<li><a href="#org324f729">2.4.3. Test</a></li>
</ul>
</li>
<li><a href="#org056cef2">2.5. Generate initial coordinates</a></li>
</ul>
</li>
</ul>
</div>
</div>
<div id="outline-container-org1c1356c" class="outline-2">
<h2 id="org1c1356c"><span class="section-number-2">1</span> Context</h2>
<div class="outline-text-2" id="text-1">
<p>
The following data stored in the context:
</p>
<table border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides">
<colgroup>
<col class="org-left" />
<col class="org-left" />
<col class="org-left" />
</colgroup>
<thead>
<tr>
<th scope="col" class="org-left">Variable</th>
<th scope="col" class="org-left">Type</th>
<th scope="col" class="org-left">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td class="org-left"><code>uninitialized</code></td>
<td class="org-left"><code>int32_t</code></td>
<td class="org-left">Keeps bit set for uninitialized data</td>
</tr>
<tr>
<td class="org-left"><code>num</code></td>
<td class="org-left"><code>int64_t</code></td>
<td class="org-left">Total number of electrons</td>
</tr>
<tr>
<td class="org-left"><code>up_num</code></td>
<td class="org-left"><code>int64_t</code></td>
<td class="org-left">Number of up-spin electrons</td>
</tr>
<tr>
<td class="org-left"><code>down_num</code></td>
<td class="org-left"><code>int64_t</code></td>
<td class="org-left">Number of down-spin electrons</td>
</tr>
<tr>
<td class="org-left"><code>provided</code></td>
<td class="org-left"><code>bool</code></td>
<td class="org-left">If true, <code>electron</code> is valid</td>
</tr>
<tr>
<td class="org-left"><code>walker</code></td>
<td class="org-left"><code>qmckl_point</code></td>
<td class="org-left">Current set of walkers</td>
</tr>
<tr>
<td class="org-left"><code>walker_old</code></td>
<td class="org-left"><code>qmckl_point</code></td>
<td class="org-left">Previous set of walkers</td>
</tr>
</tbody>
</table>
<p>
Computed data:
</p>
<table border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides">
<colgroup>
<col class="org-left" />
<col class="org-left" />
<col class="org-left" />
</colgroup>
<thead>
<tr>
<th scope="col" class="org-left">Variable</th>
<th scope="col" class="org-left">Type</th>
<th scope="col" class="org-left">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td class="org-left"><code>ee_distance</code></td>
<td class="org-left"><code>double[walker.num][num][num]</code></td>
<td class="org-left">Electron-electron distances</td>
</tr>
<tr>
<td class="org-left"><code>ee_distance_date</code></td>
<td class="org-left"><code>uint64_t</code></td>
<td class="org-left">Last modification date of the electron-electron distances</td>
</tr>
<tr>
<td class="org-left"><code>en_distance</code></td>
<td class="org-left"><code>double[num][nucl_num]</code></td>
<td class="org-left">Electron-nucleus distances</td>
</tr>
<tr>
<td class="org-left"><code>en_distance_date</code></td>
<td class="org-left"><code>uint64_t</code></td>
<td class="org-left">Last modification date of the electron-electron distances</td>
</tr>
<tr>
<td class="org-left"><code>ee_potential</code></td>
<td class="org-left"><code>double[walker.num]</code></td>
<td class="org-left">Electron-electron potential energy</td>
</tr>
<tr>
<td class="org-left"><code>ee_potential_date</code></td>
<td class="org-left"><code>uint64_t</code></td>
<td class="org-left">Last modification date of the electron-electron potential</td>
</tr>
<tr>
<td class="org-left"><code>en_potential</code></td>
<td class="org-left"><code>double[walker.num]</code></td>
<td class="org-left">Electron-nucleus potential energy</td>
</tr>
<tr>
<td class="org-left"><code>en_potential_date</code></td>
<td class="org-left"><code>int64_t</code></td>
<td class="org-left">Date when the electron-nucleus potential energy was computed</td>
</tr>
</tbody>
</table>
</div>
<div id="outline-container-org15fab56" class="outline-3">
<h3 id="org15fab56"><span class="section-number-3">1.1</span> Data structure</h3>
<div class="outline-text-3" id="text-1-1">
<div class="org-src-container">
<pre class="src src-c">
<span style="color: #a020f0;">typedef</span> <span style="color: #a020f0;">struct</span> <span style="color: #228b22;">qmckl_walker_struct</span> {
<span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">num</span>;
<span style="color: #228b22;">qmckl_point_struct</span> <span style="color: #a0522d;">point</span>;
} <span style="color: #228b22;">qmckl_walker</span>;
<span style="color: #a020f0;">typedef</span> <span style="color: #a020f0;">struct</span> <span style="color: #228b22;">qmckl_electron_struct</span> {
<span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">num</span>;
<span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">up_num</span>;
<span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">down_num</span>;
<span style="color: #228b22;">qmckl_walker</span> <span style="color: #a0522d;">walker</span>;
<span style="color: #228b22;">qmckl_walker</span> <span style="color: #a0522d;">walker_old</span>;
<span style="color: #228b22;">uint64_t</span> <span style="color: #a0522d;">ee_distance_date</span>;
<span style="color: #228b22;">uint64_t</span> <span style="color: #a0522d;">en_distance_date</span>;
<span style="color: #228b22;">uint64_t</span> <span style="color: #a0522d;">ee_potential_date</span>;
<span style="color: #228b22;">uint64_t</span> <span style="color: #a0522d;">en_potential_date</span>;
<span style="color: #228b22;">double</span>* <span style="color: #a0522d;">ee_distance</span>;
<span style="color: #228b22;">double</span>* <span style="color: #a0522d;">en_distance</span>;
<span style="color: #228b22;">double</span>* <span style="color: #a0522d;">ee_potential</span>;
<span style="color: #228b22;">double</span>* <span style="color: #a0522d;">en_potential</span>;
<span style="color: #228b22;">int32_t</span> <span style="color: #a0522d;">uninitialized</span>;
<span style="color: #228b22;">bool</span> <span style="color: #a0522d;">provided</span>;
} <span style="color: #228b22;">qmckl_electron_struct</span>;
</pre>
</div>
<p>
The <code>uninitialized</code> integer contains one bit set to one for each
initialization function which has not been called. It becomes equal
to zero after all initialization functions have been called. The
struct is then initialized and <code>provided == true</code>.
Some values are initialized by default, and are not concerned by
this mechanism.
</p>
<div class="org-src-container">
<pre class="src src-c"><span style="color: #228b22;">qmckl_exit_code</span> <span style="color: #0000ff;">qmckl_init_electron</span>(<span style="color: #228b22;">qmckl_context</span> <span style="color: #a0522d;">context</span>);
</pre>
</div>
<div class="org-src-container">
<pre class="src src-c"><span style="color: #228b22;">qmckl_exit_code</span> <span style="color: #0000ff;">qmckl_init_electron</span>(<span style="color: #228b22;">qmckl_context</span> <span style="color: #a0522d;">context</span>) {
<span style="color: #a020f0;">if</span> (qmckl_context_check(context) == QMCKL_NULL_CONTEXT) {
<span style="color: #a020f0;">return</span> <span style="color: #008b8b;">false</span>;
}
<span style="color: #228b22;">qmckl_context_struct</span>* <span style="color: #a020f0;">const</span> <span style="color: #a0522d;">ctx</span> = (<span style="color: #228b22;">qmckl_context_struct</span>*) context;
assert (ctx != <span style="color: #008b8b;">NULL</span>);
ctx-&gt;electron.uninitialized = (1 &lt;&lt; 1) - 1;
<span style="color: #a020f0;">return</span> QMCKL_SUCCESS;
}
</pre>
</div>
<div class="org-src-container">
<pre class="src src-c"><span style="color: #228b22;">bool</span> <span style="color: #0000ff;">qmckl_electron_provided</span> (<span style="color: #a020f0;">const</span> <span style="color: #228b22;">qmckl_context</span> <span style="color: #a0522d;">context</span>);
</pre>
</div>
</div>
</div>
<div id="outline-container-org6bb5fa1" class="outline-3">
<h3 id="org6bb5fa1"><span class="section-number-3">1.2</span> Initialization functions</h3>
<div class="outline-text-3" id="text-1-2">
<p>
To set the data relative to the electrons in the context, the
following functions need to be called. When the data structure is
initialized, the internal <code>coord_new</code> and <code>coord_old</code> arrays are
both not allocated.
</p>
<div class="org-src-container">
<pre class="src src-c"><span style="color: #228b22;">qmckl_exit_code</span> <span style="color: #0000ff;">qmckl_set_electron_num</span> (<span style="color: #228b22;">qmckl_context</span> <span style="color: #a0522d;">context</span>, <span style="color: #a020f0;">const</span> <span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">up_num</span>, <span style="color: #a020f0;">const</span> <span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">down_num</span>);
<span style="color: #228b22;">qmckl_exit_code</span> <span style="color: #0000ff;">qmckl_set_electron_coord</span> (<span style="color: #228b22;">qmckl_context</span> <span style="color: #a0522d;">context</span>, <span style="color: #a020f0;">const</span> <span style="color: #228b22;">char</span> <span style="color: #a0522d;">transp</span>, <span style="color: #a020f0;">const</span> <span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">walk_num</span>, <span style="color: #a020f0;">const</span> <span style="color: #228b22;">double</span>* <span style="color: #a0522d;">coord</span>, <span style="color: #a020f0;">const</span> <span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">size_max</span>);
</pre>
</div>
<p>
To set the number of electrons, we give the number of up-spin and
down-spin electrons to the context and we set the number of walkers.
</p>
<div class="org-src-container">
<pre class="src src-f90"><span style="color: #a020f0;">interface</span>
<span style="color: #228b22;">integer</span>(<span style="color: #008b8b;">c_int32_t</span>) <span style="color: #a020f0;">function</span> <span style="color: #0000ff;">qmckl_set_electron_num</span>(context, alpha, beta) <span style="color: #a020f0;">bind</span>(C)
<span style="color: #a020f0;">use</span>, <span style="color: #a020f0;">intrinsic</span> :: <span style="color: #0000ff;">iso_c_binding</span>
<span style="color: #a020f0;">import</span>
<span style="color: #a020f0;">implicit</span> <span style="color: #228b22;">none</span>
<span style="color: #228b22;">integer</span> (<span style="color: #008b8b;">c_int64_t</span>) , <span style="color: #a020f0;">intent</span>(in) , <span style="color: #a020f0;">value</span> ::<span style="color: #a0522d;"> context</span>
<span style="color: #228b22;">integer</span> (<span style="color: #008b8b;">c_int64_t</span>) , <span style="color: #a020f0;">intent</span>(in) , <span style="color: #a020f0;">value</span> ::<span style="color: #a0522d;"> alpha</span>
<span style="color: #228b22;">integer</span> (<span style="color: #008b8b;">c_int64_t</span>) , <span style="color: #a020f0;">intent</span>(in) , <span style="color: #a020f0;">value</span> ::<span style="color: #a0522d;"> beta</span>
<span style="color: #a020f0;">end function</span>
<span style="color: #a020f0;">end interface</span>
</pre>
</div>
<p>
The following function sets the electron coordinates of all the
walkers. When this is done, the pointers to the old and new sets
of coordinates are swapped, and the new coordinates are
overwritten. This can be done only when the data relative to
electrons have been set.
</p>
<p>
<code>size_max</code> should be equal equal or geater than <code>elec_num *
walker.num * 3</code>, to be symmetric with <code>qmckl_get_electron_coord</code>.
</p>
<p>
Important: changing the electron coordinates increments the date
in the context.
</p>
<div class="org-src-container">
<pre class="src src-f90"><span style="color: #a020f0;">interface</span>
<span style="color: #228b22;">integer</span>(<span style="color: #008b8b;">c_int32_t</span>) <span style="color: #a020f0;">function</span> <span style="color: #0000ff;">qmckl_set_electron_coord</span>(context, transp, walk_num, coord, size_max) <span style="color: #a020f0;">bind</span>(C)
<span style="color: #a020f0;">use</span>, <span style="color: #a020f0;">intrinsic</span> :: <span style="color: #0000ff;">iso_c_binding</span>
<span style="color: #a020f0;">import</span>
<span style="color: #a020f0;">implicit</span> <span style="color: #228b22;">none</span>
<span style="color: #228b22;">integer</span> (<span style="color: #008b8b;">c_int64_t</span>) , <span style="color: #a020f0;">intent</span>(in) , <span style="color: #a020f0;">value</span> ::<span style="color: #a0522d;"> context</span>
<span style="color: #228b22;">character</span>(<span style="color: #008b8b;">c_char</span>) , <span style="color: #a020f0;">intent</span>(in) , <span style="color: #a020f0;">value</span> ::<span style="color: #a0522d;"> transp</span>
<span style="color: #228b22;">integer</span> (<span style="color: #008b8b;">c_int64_t</span>) , <span style="color: #a020f0;">intent</span>(in) , <span style="color: #a020f0;">value</span> ::<span style="color: #a0522d;"> walk_num</span>
<span style="color: #228b22;">real</span>(<span style="color: #008b8b;">c_double</span>) , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> coord(*)</span>
<span style="color: #228b22;">integer</span> (<span style="color: #008b8b;">c_int64_t</span>) , <span style="color: #a020f0;">intent</span>(in) , <span style="color: #a020f0;">value</span> ::<span style="color: #a0522d;"> size_max</span>
<span style="color: #a020f0;">end function</span>
<span style="color: #a020f0;">end interface</span>
</pre>
</div>
</div>
</div>
<div id="outline-container-org148643a" class="outline-3">
<h3 id="org148643a"><span class="section-number-3">1.3</span> Access functions</h3>
<div class="outline-text-3" id="text-1-3">
<p>
Access functions return <code>QMCKL_SUCCESS</code> when the data has been
successfully retrieved. It returnes <code>QMCKL_INVALID_CONTEXT</code> when
the context is not a valid context, and <code>QMCKL_NOT_PROVIDED</code> when
the data has not been provided. If the function returns
successfully, the variable pointed by the pointer given in argument
contains the requested data. Otherwise, this variable is untouched.
</p>
</div>
<div id="outline-container-orgd3cec20" class="outline-4">
<h4 id="orgd3cec20"><span class="section-number-4">1.3.1</span> Number of electrons</h4>
</div>
<div id="outline-container-orgc0c2b28" class="outline-4">
<h4 id="orgc0c2b28"><span class="section-number-4">1.3.2</span> Number of walkers</h4>
<div class="outline-text-4" id="text-1-3-2">
<p>
A walker is a set of electron coordinates that are arguments of
the wave function. <code>walk_num</code> is the number of walkers.
</p>
</div>
</div>
<div id="outline-container-orgd35c18c" class="outline-4">
<h4 id="orgd35c18c"><span class="section-number-4">1.3.3</span> Electron coordinates</h4>
<div class="outline-text-4" id="text-1-3-3">
<p>
Returns the current electron coordinates. The pointer is assumed
to point on a memory block of size <code>size_max</code> &ge; <code>3 * elec_num * walker.num</code>.
The order of the indices is:
</p>
<table border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides">
<colgroup>
<col class="org-left" />
<col class="org-left" />
<col class="org-left" />
</colgroup>
<thead>
<tr>
<th scope="col" class="org-left">&#xa0;</th>
<th scope="col" class="org-left">Normal</th>
<th scope="col" class="org-left">Transposed</th>
</tr>
</thead>
<tbody>
<tr>
<td class="org-left">C</td>
<td class="org-left"><code>[walker.num*elec_num][3]</code></td>
<td class="org-left"><code>[3][walker.num*elec_num]</code></td>
</tr>
<tr>
<td class="org-left">Fortran</td>
<td class="org-left"><code>(3,walker.num*elec_num)</code></td>
<td class="org-left"><code>(walker.num*elec_num, 3)</code></td>
</tr>
</tbody>
</table>
<p>
As the <code>walker</code> attribute is equal to <code>points</code>, returning the
current electron coordinates is equivalent to returning the
current points.
</p>
<div class="org-src-container">
<pre class="src src-f90"><span style="color: #a020f0;">interface</span>
<span style="color: #228b22;">integer</span>(<span style="color: #008b8b;">c_int32_t</span>) <span style="color: #a020f0;">function</span> <span style="color: #0000ff;">qmckl_get_electron_coord</span>(context, transp, coord, size_max) <span style="color: #a020f0;">bind</span>(C)
<span style="color: #a020f0;">use</span>, <span style="color: #a020f0;">intrinsic</span> :: <span style="color: #0000ff;">iso_c_binding</span>
<span style="color: #a020f0;">import</span>
<span style="color: #a020f0;">implicit</span> <span style="color: #228b22;">none</span>
<span style="color: #228b22;">integer</span> (<span style="color: #008b8b;">c_int64_t</span>) , <span style="color: #a020f0;">intent</span>(in) , <span style="color: #a020f0;">value</span> ::<span style="color: #a0522d;"> context</span>
<span style="color: #228b22;">character</span>(<span style="color: #008b8b;">c_char</span>) , <span style="color: #a020f0;">intent</span>(in) , <span style="color: #a020f0;">value</span> ::<span style="color: #a0522d;"> transp</span>
<span style="color: #228b22;">real</span>(<span style="color: #008b8b;">c_double</span>) , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> coord(*)</span>
<span style="color: #228b22;">integer</span> (<span style="color: #008b8b;">c_int64_t</span>) , <span style="color: #a020f0;">intent</span>(in) , <span style="color: #a020f0;">value</span> ::<span style="color: #a0522d;"> size_max</span>
<span style="color: #a020f0;">end function</span>
<span style="color: #a020f0;">end interface</span>
</pre>
</div>
</div>
</div>
</div>
<div id="outline-container-org1b334dc" class="outline-3">
<h3 id="org1b334dc"><span class="section-number-3">1.4</span> Test</h3>
<div class="outline-text-3" id="text-1-4">
<div class="org-src-container">
<pre class="src src-c">/* <span style="color: #b22222;">Reference input data</span> */
<span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">walk_num</span> = chbrclf_walk_num;
<span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">elec_num</span> = chbrclf_elec_num;
<span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">elec_up_num</span> = chbrclf_elec_up_num;
<span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">elec_dn_num</span> = chbrclf_elec_dn_num;
<span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">nucl_num</span> = chbrclf_nucl_num;
<span style="color: #228b22;">double</span>* <span style="color: #a0522d;">charge</span> = chbrclf_charge;
<span style="color: #228b22;">double</span>* <span style="color: #a0522d;">nucl_coord</span> = &amp;(chbrclf_nucl_coord[0][0]);
<span style="color: #228b22;">double</span>* <span style="color: #a0522d;">elec_coord</span> = &amp;(chbrclf_elec_coord[0][0][0]);
/* <span style="color: #b22222;">---</span> */
<span style="color: #228b22;">qmckl_exit_code</span> <span style="color: #a0522d;">rc</span>;
assert(!qmckl_electron_provided(context));
<span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">n</span>;
rc = qmckl_get_electron_num (context, &amp;n);
<span style="color: #0000ff;">assert</span>(rc == QMCKL_NOT_PROVIDED);
rc = qmckl_get_electron_up_num (context, &amp;n);
<span style="color: #0000ff;">assert</span>(rc == QMCKL_NOT_PROVIDED);
rc = qmckl_get_electron_down_num (context, &amp;n);
<span style="color: #0000ff;">assert</span>(rc == QMCKL_NOT_PROVIDED);
rc = qmckl_set_electron_num (context, elec_up_num, elec_dn_num);
<span style="color: #0000ff;">qmckl_check</span>(context, rc);
<span style="color: #0000ff;">assert</span>(<span style="color: #228b22;">qmckl_electron_provided</span>(<span style="color: #a0522d;">context</span>));
rc = qmckl_get_electron_up_num (context, &amp;n);
<span style="color: #0000ff;">qmckl_check</span>(context, rc);
<span style="color: #0000ff;">assert</span>(n == elec_up_num);
rc = qmckl_get_electron_down_num (context, &amp;n);
<span style="color: #0000ff;">qmckl_check</span>(context, rc);
<span style="color: #0000ff;">assert</span>(n == elec_dn_num);
rc = qmckl_get_electron_num (context, &amp;n);
<span style="color: #0000ff;">qmckl_check</span>(context, rc);
<span style="color: #0000ff;">assert</span>(n == elec_num);
<span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">w</span> = 0;
rc = qmckl_get_electron_walk_num (context, &amp;w);
<span style="color: #0000ff;">qmckl_check</span>(context, rc);
<span style="color: #0000ff;">assert</span>(w == 0);
<span style="color: #0000ff;">assert</span>(<span style="color: #228b22;">qmckl_electron_provided</span>(<span style="color: #a0522d;">context</span>));
rc = qmckl_set_electron_coord (context, <span style="color: #8b2252;">'N'</span>, walk_num, elec_coord, walk_num*elec_num*3);
<span style="color: #0000ff;">qmckl_check</span>(context, rc);
rc = qmckl_get_electron_walk_num (context, &amp;w);
<span style="color: #0000ff;">qmckl_check</span>(context, rc);
<span style="color: #0000ff;">assert</span>(w == walk_num);
<span style="color: #228b22;">double</span> <span style="color: #a0522d;">elec_coord2</span>[walk_num*3*elec_num];
rc = qmckl_get_electron_coord (context, <span style="color: #8b2252;">'N'</span>, elec_coord2, walk_num*3*elec_num);
<span style="color: #0000ff;">qmckl_check</span>(context, rc);
<span style="color: #a020f0;">for</span> (<span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">i</span>=0 ; i&lt;3*elec_num*walk_num ; ++i) {
printf(<span style="color: #8b2252;">"%f %f\n"</span>, elec_coord[i], elec_coord2[i]);
assert( elec_coord[i] == elec_coord2[i] );
}
</pre>
</div>
</div>
</div>
</div>
<div id="outline-container-orgdc6fbed" class="outline-2">
<h2 id="orgdc6fbed"><span class="section-number-2">2</span> Computation</h2>
<div class="outline-text-2" id="text-2">
<p>
The computed data is stored in the context so that it can be reused
by different kernels. To ensure that the data is valid, for each
computed data the date of the context is stored when it is computed.
To know if some data needs to be recomputed, we check if the date of
the dependencies are more recent than the date of the data to
compute. If it is the case, then the data is recomputed and the
current date is stored.
</p>
</div>
<div id="outline-container-org27ac20c" class="outline-3">
<h3 id="org27ac20c"><span class="section-number-3">2.1</span> Electron-electron distances</h3>
<div class="outline-text-3" id="text-2-1">
</div>
<div id="outline-container-org0579ccb" class="outline-4">
<h4 id="org0579ccb"><span class="section-number-4">2.1.1</span> Get</h4>
<div class="outline-text-4" id="text-2-1-1">
<div class="org-src-container">
<pre class="src src-c"><span style="color: #228b22;">qmckl_exit_code</span> <span style="color: #0000ff;">qmckl_get_electron_ee_distance</span>(<span style="color: #228b22;">qmckl_context</span> <span style="color: #a0522d;">context</span>, <span style="color: #228b22;">double</span>* <span style="color: #a020f0;">const</span> <span style="color: #a0522d;">distance</span>);
</pre>
</div>
</div>
</div>
<div id="outline-container-orga29444d" class="outline-4">
<h4 id="orga29444d"><span class="section-number-4">2.1.2</span> Compute</h4>
<div class="outline-text-4" id="text-2-1-2">
<table id="orgc903777" border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides">
<colgroup>
<col class="org-left" />
<col class="org-left" />
<col class="org-left" />
<col class="org-left" />
</colgroup>
<thead>
<tr>
<th scope="col" class="org-left">Variable</th>
<th scope="col" class="org-left">Type</th>
<th scope="col" class="org-left">In/Out</th>
<th scope="col" class="org-left">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td class="org-left"><code>context</code></td>
<td class="org-left"><code>qmckl_context</code></td>
<td class="org-left">in</td>
<td class="org-left">Global state</td>
</tr>
<tr>
<td class="org-left"><code>elec_num</code></td>
<td class="org-left"><code>int64_t</code></td>
<td class="org-left">in</td>
<td class="org-left">Number of electrons</td>
</tr>
<tr>
<td class="org-left"><code>walk_num</code></td>
<td class="org-left"><code>int64_t</code></td>
<td class="org-left">in</td>
<td class="org-left">Number of walkers</td>
</tr>
<tr>
<td class="org-left"><code>coord</code></td>
<td class="org-left"><code>double[3][walk_num][elec_num]</code></td>
<td class="org-left">in</td>
<td class="org-left">Electron coordinates</td>
</tr>
<tr>
<td class="org-left"><code>ee_distance</code></td>
<td class="org-left"><code>double[walk_num][elec_num][elec_num]</code></td>
<td class="org-left">out</td>
<td class="org-left">Electron-electron distances</td>
</tr>
</tbody>
</table>
<div class="org-src-container">
<pre class="src src-f90"><span style="color: #228b22;">integer </span><span style="color: #a020f0;">function</span><span style="color: #a0522d;"> </span><span style="color: #0000ff;">qmckl_compute_ee_distance_f</span><span style="color: #000000; background-color: #ffffff;">(context, elec_num, walk_num, coord, ee_distance)</span><span style="color: #a0522d;"> </span><span style="color: #a020f0;">&amp;</span>
<span style="color: #a020f0;">result</span>(info)
<span style="color: #a020f0;">use</span> <span style="color: #0000ff;">qmckl</span>
<span style="color: #a020f0;">implicit</span> <span style="color: #228b22;">none</span>
<span style="color: #228b22;">integer</span>(qmckl_context), <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> context</span>
<span style="color: #228b22;">integer</span>*8 , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> elec_num</span>
<span style="color: #228b22;">integer</span>*8 , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> walk_num</span>
<span style="color: #228b22;">double precision</span> , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> coord(elec_num,walk_num,3)</span>
<span style="color: #228b22;">double precision</span> , <span style="color: #a020f0;">intent</span>(out) ::<span style="color: #a0522d;"> ee_distance(elec_num,elec_num,walk_num)</span>
<span style="color: #228b22;">integer</span>*8 ::<span style="color: #a0522d;"> k, i, j</span>
<span style="color: #228b22;">double precision</span> ::<span style="color: #a0522d;"> x, y, z</span>
info = QMCKL_SUCCESS
<span style="color: #a020f0;">if</span> (context == QMCKL_NULL_CONTEXT) <span style="color: #a020f0;">then</span>
info = QMCKL_INVALID_CONTEXT
<span style="color: #a020f0;">return</span>
<span style="color: #a020f0;">endif</span>
<span style="color: #a020f0;">if</span> (elec_num &lt;= 0) <span style="color: #a020f0;">then</span>
info = QMCKL_INVALID_ARG_2
<span style="color: #a020f0;">return</span>
<span style="color: #a020f0;">endif</span>
<span style="color: #a020f0;">if</span> (walk_num &lt;= 0) <span style="color: #a020f0;">then</span>
info = QMCKL_INVALID_ARG_3
<span style="color: #a020f0;">return</span>
<span style="color: #a020f0;">endif</span>
<span style="color: #a020f0;">do</span> k=1,walk_num
info = qmckl_distance(context, <span style="color: #8b2252;">'T'</span>, <span style="color: #8b2252;">'T'</span>, elec_num, elec_num, <span style="color: #a020f0;">&amp;</span>
coord(1,k,1), elec_num * walk_num, <span style="color: #a020f0;">&amp;</span>
coord(1,k,1), elec_num * walk_num, <span style="color: #a020f0;">&amp;</span>
ee_distance(1,1,k), elec_num)
<span style="color: #a020f0;">if</span> (info /= QMCKL_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">exit</span>
<span style="color: #a020f0;">endif</span>
<span style="color: #a020f0;">end do</span>
<span style="color: #a020f0;">end function</span> <span style="color: #0000ff;">qmckl_compute_ee_distance_f</span>
</pre>
</div>
</div>
</div>
<div id="outline-container-orgbac7d2b" class="outline-4">
<h4 id="orgbac7d2b"><span class="section-number-4">2.1.3</span> Test</h4>
<div class="outline-text-4" id="text-2-1-3">
<div class="org-src-container">
<pre class="src src-c"><span style="color: #0000ff;">assert</span>(<span style="color: #228b22;">qmckl_electron_provided</span>(<span style="color: #a0522d;">context</span>));
<span style="color: #228b22;">double</span> <span style="color: #a0522d;">ee_distance</span>[walk_num * elec_num * elec_num];
rc = qmckl_get_electron_ee_distance(context, ee_distance);
// <span style="color: #b22222;">(e1,e2,w)</span>
// <span style="color: #b22222;">(0,0,0) == 0.</span>
<span style="color: #0000ff;">assert</span>(<span style="color: #228b22;">ee_distance</span>[0] == 0.);
// <span style="color: #b22222;">(1,0,0) == (0,1,0)</span>
<span style="color: #0000ff;">assert</span>(<span style="color: #228b22;">ee_distance</span>[1] == ee_distance[elec_num]);
// <span style="color: #b22222;">value of (1,0,0)</span>
<span style="color: #0000ff;">assert</span>(fabs(<span style="color: #228b22;">ee_distance</span>[1]-7.152322512964209) &lt; 1.e-12);
// <span style="color: #b22222;">(0,0,1) == 0.</span>
<span style="color: #0000ff;">assert</span>(<span style="color: #228b22;">ee_distance</span>[elec_num*elec_num] == 0.);
// <span style="color: #b22222;">(1,0,1) == (0,1,1)</span>
<span style="color: #0000ff;">assert</span>(<span style="color: #228b22;">ee_distance</span>[elec_num*elec_num+1] == ee_distance[elec_num*elec_num+elec_num]);
// <span style="color: #b22222;">value of (1,0,1)</span>
<span style="color: #0000ff;">assert</span>(fabs(<span style="color: #228b22;">ee_distance</span>[elec_num*elec_num+1]-6.5517646321055665) &lt; 1.e-12);
</pre>
</div>
</div>
</div>
</div>
<div id="outline-container-org29a7e21" class="outline-3">
<h3 id="org29a7e21"><span class="section-number-3">2.2</span> Electron-electron potential</h3>
<div class="outline-text-3" id="text-2-2">
<p>
<code>ee_potential</code> is given by
</p>
<p>
\[
\mathcal{V}_{ee} = \sum_{i=1}^{N_e}\sum_{j>i}^{N_e}\frac{1}{r_{ij}}
\]
</p>
<p>
where \(\mathcal{V}_{ee}\) is the <code>ee</code> potential and \[r_{ij}\] the <code>ee</code>
distance.
</p>
</div>
<div id="outline-container-orga611bf8" class="outline-4">
<h4 id="orga611bf8"><span class="section-number-4">2.2.1</span> Get</h4>
<div class="outline-text-4" id="text-2-2-1">
<div class="org-src-container">
<pre class="src src-c"><span style="color: #228b22;">qmckl_exit_code</span> <span style="color: #0000ff;">qmckl_get_electron_ee_potential</span>(<span style="color: #228b22;">qmckl_context</span> <span style="color: #a0522d;">context</span>, <span style="color: #228b22;">double</span>* <span style="color: #a020f0;">const</span> <span style="color: #a0522d;">ee_potential</span>);
</pre>
</div>
</div>
</div>
<div id="outline-container-org3f78270" class="outline-4">
<h4 id="org3f78270"><span class="section-number-4">2.2.2</span> Compute</h4>
<div class="outline-text-4" id="text-2-2-2">
<table id="org3b41862" border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides">
<colgroup>
<col class="org-left" />
<col class="org-left" />
<col class="org-left" />
<col class="org-left" />
</colgroup>
<thead>
<tr>
<th scope="col" class="org-left">Variable</th>
<th scope="col" class="org-left">Type</th>
<th scope="col" class="org-left">In/Out</th>
<th scope="col" class="org-left">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td class="org-left"><code>context</code></td>
<td class="org-left"><code>qmckl_context</code></td>
<td class="org-left">in</td>
<td class="org-left">Global state</td>
</tr>
<tr>
<td class="org-left"><code>elec_num</code></td>
<td class="org-left"><code>int64_t</code></td>
<td class="org-left">in</td>
<td class="org-left">Number of electrons</td>
</tr>
<tr>
<td class="org-left"><code>walk_num</code></td>
<td class="org-left"><code>int64_t</code></td>
<td class="org-left">in</td>
<td class="org-left">Number of walkers</td>
</tr>
<tr>
<td class="org-left"><code>ee_distance</code></td>
<td class="org-left"><code>double[walk_num][elec_num][elec_num]</code></td>
<td class="org-left">in</td>
<td class="org-left">Electron-electron distances</td>
</tr>
<tr>
<td class="org-left"><code>ee_potential</code></td>
<td class="org-left"><code>double[walk_num]</code></td>
<td class="org-left">out</td>
<td class="org-left">Electron-electron potential</td>
</tr>
</tbody>
</table>
<div class="org-src-container">
<pre class="src src-f90"><span style="color: #228b22;">integer</span><span style="color: #a0522d;"> function qmckl_compute_ee_potential_f(context, elec_num, walk_num, </span><span style="color: #a020f0;">&amp;</span>
ee_distance, ee_potential) <span style="color: #a020f0;">&amp;</span>
<span style="color: #a020f0;">result</span>(info)
<span style="color: #a020f0;">use</span> <span style="color: #0000ff;">qmckl</span>
<span style="color: #a020f0;">implicit</span> <span style="color: #228b22;">none</span>
<span style="color: #228b22;">integer</span>(qmckl_context), <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> context</span>
<span style="color: #228b22;">integer</span>*8 , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> elec_num</span>
<span style="color: #228b22;">integer</span>*8 , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> walk_num</span>
<span style="color: #228b22;">double precision</span> , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> ee_distance(elec_num,elec_num,walk_num)</span>
<span style="color: #228b22;">double precision</span> , <span style="color: #a020f0;">intent</span>(out) ::<span style="color: #a0522d;"> ee_potential(walk_num)</span>
<span style="color: #228b22;">integer</span>*8 ::<span style="color: #a0522d;"> nw, i, j</span>
info = QMCKL_SUCCESS
<span style="color: #a020f0;">if</span> (context == QMCKL_NULL_CONTEXT) <span style="color: #a020f0;">then</span>
info = QMCKL_INVALID_CONTEXT
<span style="color: #a020f0;">return</span>
<span style="color: #a020f0;">endif</span>
<span style="color: #a020f0;">if</span> (elec_num &lt;= 0) <span style="color: #a020f0;">then</span>
info = QMCKL_INVALID_ARG_2
<span style="color: #a020f0;">return</span>
<span style="color: #a020f0;">endif</span>
<span style="color: #a020f0;">if</span> (walk_num &lt;= 0) <span style="color: #a020f0;">then</span>
info = QMCKL_INVALID_ARG_3
<span style="color: #a020f0;">return</span>
<span style="color: #a020f0;">endif</span>
ee_potential = 0.0d0
<span style="color: #a020f0;">do</span> nw=1,walk_num
<span style="color: #a020f0;">do</span> j=2,elec_num
<span style="color: #a020f0;">do</span> i=1,j-1
<span style="color: #a020f0;">if</span> (dabs(ee_distance(i,j,nw)) &gt; 1e-5) <span style="color: #a020f0;">then</span>
ee_potential(nw) = ee_potential(nw) + 1.0d0/(ee_distance(i,j,nw))
<span style="color: #a020f0;">endif</span>
<span style="color: #a020f0;">end do</span>
<span style="color: #a020f0;">end do</span>
<span style="color: #a020f0;">end do</span>
<span style="color: #a020f0;">end function</span> <span style="color: #0000ff;">qmckl_compute_ee_potential_f</span>
</pre>
</div>
<div class="org-src-container">
<pre class="src src-c"><span style="color: #228b22;">qmckl_exit_code</span> <span style="color: #0000ff;">qmckl_compute_ee_potential</span> (
<span style="color: #a020f0;">const</span> <span style="color: #228b22;">qmckl_context</span> <span style="color: #a0522d;">context</span>,
<span style="color: #a020f0;">const</span> <span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">elec_num</span>,
<span style="color: #a020f0;">const</span> <span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">walk_num</span>,
<span style="color: #a020f0;">const</span> <span style="color: #228b22;">double</span>* <span style="color: #a0522d;">ee_distance</span>,
<span style="color: #228b22;">double</span>* <span style="color: #a020f0;">const</span> <span style="color: #a0522d;">ee_potential</span> );
</pre>
</div>
</div>
</div>
<div id="outline-container-orga2c1d7d" class="outline-4">
<h4 id="orga2c1d7d"><span class="section-number-4">2.2.3</span> Test</h4>
<div class="outline-text-4" id="text-2-2-3">
<div class="org-src-container">
<pre class="src src-c"><span style="color: #228b22;">double</span> <span style="color: #a0522d;">ee_potential</span>[walk_num];
rc = qmckl_get_electron_ee_potential(context, &amp;(ee_potential[0]));
<span style="color: #0000ff;">qmckl_check</span>(context, rc);
</pre>
</div>
</div>
</div>
</div>
<div id="outline-container-orga7496f3" class="outline-3">
<h3 id="orga7496f3"><span class="section-number-3">2.3</span> Electron-nucleus distances</h3>
<div class="outline-text-3" id="text-2-3">
</div>
<div id="outline-container-org0614625" class="outline-4">
<h4 id="org0614625"><span class="section-number-4">2.3.1</span> Get</h4>
<div class="outline-text-4" id="text-2-3-1">
<div class="org-src-container">
<pre class="src src-c"><span style="color: #228b22;">qmckl_exit_code</span> <span style="color: #0000ff;">qmckl_get_electron_en_distance</span>(<span style="color: #228b22;">qmckl_context</span> <span style="color: #a0522d;">context</span>, <span style="color: #228b22;">double</span>* <span style="color: #a0522d;">distance</span>);
</pre>
</div>
</div>
</div>
<div id="outline-container-orgc1c1fbd" class="outline-4">
<h4 id="orgc1c1fbd"><span class="section-number-4">2.3.2</span> Compute</h4>
<div class="outline-text-4" id="text-2-3-2">
<table id="org9f2ae60" border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides">
<colgroup>
<col class="org-left" />
<col class="org-left" />
<col class="org-left" />
<col class="org-left" />
</colgroup>
<thead>
<tr>
<th scope="col" class="org-left">Variable</th>
<th scope="col" class="org-left">Type</th>
<th scope="col" class="org-left">In/Out</th>
<th scope="col" class="org-left">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td class="org-left"><code>context</code></td>
<td class="org-left"><code>qmckl_context</code></td>
<td class="org-left">in</td>
<td class="org-left">Global state</td>
</tr>
<tr>
<td class="org-left"><code>point_num</code></td>
<td class="org-left"><code>int64_t</code></td>
<td class="org-left">in</td>
<td class="org-left">Number of points</td>
</tr>
<tr>
<td class="org-left"><code>nucl_num</code></td>
<td class="org-left"><code>int64_t</code></td>
<td class="org-left">in</td>
<td class="org-left">Number of nuclei</td>
</tr>
<tr>
<td class="org-left"><code>elec_coord</code></td>
<td class="org-left"><code>double[3][point_num]</code></td>
<td class="org-left">in</td>
<td class="org-left">Electron coordinates</td>
</tr>
<tr>
<td class="org-left"><code>nucl_coord</code></td>
<td class="org-left"><code>double[3][nucl_num]</code></td>
<td class="org-left">in</td>
<td class="org-left">Nuclear coordinates</td>
</tr>
<tr>
<td class="org-left"><code>en_distance</code></td>
<td class="org-left"><code>double[point_num][nucl_num]</code></td>
<td class="org-left">out</td>
<td class="org-left">Electron-nucleus distances</td>
</tr>
</tbody>
</table>
<div class="org-src-container">
<pre class="src src-f90"><span style="color: #228b22;">integer </span><span style="color: #a020f0;">function</span><span style="color: #a0522d;"> </span><span style="color: #0000ff;">qmckl_compute_en_distance_f</span><span style="color: #000000; background-color: #ffffff;">(context, point_num, nucl_num, elec_coord, nucl_coord, en_distance)</span><span style="color: #a0522d;"> </span><span style="color: #a020f0;">&amp;</span>
<span style="color: #a020f0;">result</span>(info)
<span style="color: #a020f0;">use</span> <span style="color: #0000ff;">qmckl</span>
<span style="color: #a020f0;">implicit</span> <span style="color: #228b22;">none</span>
<span style="color: #228b22;">integer</span>(qmckl_context), <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> context</span>
<span style="color: #228b22;">integer</span>*8 , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> point_num</span>
<span style="color: #228b22;">integer</span>*8 , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> nucl_num</span>
<span style="color: #228b22;">double precision</span> , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> elec_coord(point_num,3)</span>
<span style="color: #228b22;">double precision</span> , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> nucl_coord(nucl_num,3)</span>
<span style="color: #228b22;">double precision</span> , <span style="color: #a020f0;">intent</span>(out) ::<span style="color: #a0522d;"> en_distance(nucl_num,point_num)</span>
<span style="color: #228b22;">integer</span>*8 ::<span style="color: #a0522d;"> k</span>
info = QMCKL_SUCCESS
<span style="color: #a020f0;">if</span> (context == QMCKL_NULL_CONTEXT) <span style="color: #a020f0;">then</span>
info = QMCKL_INVALID_CONTEXT
<span style="color: #a020f0;">return</span>
<span style="color: #a020f0;">endif</span>
<span style="color: #a020f0;">if</span> (point_num &lt;= 0) <span style="color: #a020f0;">then</span>
info = QMCKL_INVALID_ARG_2
<span style="color: #a020f0;">return</span>
<span style="color: #a020f0;">endif</span>
<span style="color: #a020f0;">if</span> (nucl_num &lt;= 0) <span style="color: #a020f0;">then</span>
info = QMCKL_INVALID_ARG_3
<span style="color: #a020f0;">return</span>
<span style="color: #a020f0;">endif</span>
info = qmckl_distance(context, <span style="color: #8b2252;">'T'</span>, <span style="color: #8b2252;">'T'</span>, nucl_num, point_num, <span style="color: #a020f0;">&amp;</span>
nucl_coord, nucl_num, <span style="color: #a020f0;">&amp;</span>
elec_coord, point_num, <span style="color: #a020f0;">&amp;</span>
en_distance, nucl_num)
<span style="color: #a020f0;">end function</span> <span style="color: #0000ff;">qmckl_compute_en_distance_f</span>
</pre>
</div>
</div>
</div>
<div id="outline-container-orgdd427ab" class="outline-4">
<h4 id="orgdd427ab"><span class="section-number-4">2.3.3</span> Test</h4>
<div class="outline-text-4" id="text-2-3-3">
<div class="org-src-container">
<pre class="src src-c">
assert(!qmckl_nucleus_provided(context));
<span style="color: #0000ff;">assert</span>(<span style="color: #228b22;">qmckl_electron_provided</span>(<span style="color: #a0522d;">context</span>));
rc = qmckl_set_nucleus_num (context, nucl_num);
<span style="color: #0000ff;">qmckl_check</span>(context, rc);
rc = qmckl_set_nucleus_charge (context, charge, nucl_num);
<span style="color: #0000ff;">qmckl_check</span>(context, rc);
rc = qmckl_set_nucleus_coord (context, <span style="color: #8b2252;">'T'</span>, nucl_coord, 3*nucl_num);
<span style="color: #0000ff;">qmckl_check</span>(context, rc);
<span style="color: #0000ff;">assert</span>(<span style="color: #228b22;">qmckl_nucleus_provided</span>(<span style="color: #a0522d;">context</span>));
<span style="color: #228b22;">double</span> <span style="color: #a0522d;">en_distance</span>[walk_num][elec_num][nucl_num];
rc = qmckl_get_electron_en_distance(context, &amp;(en_distance[0][0][0]));
<span style="color: #0000ff;">qmckl_check</span>(context, rc);
// <span style="color: #b22222;">(e,n,w) in Fortran notation</span>
// <span style="color: #b22222;">(1,1,1)</span>
<span style="color: #0000ff;">assert</span>(fabs(<span style="color: #228b22;">en_distance</span>[0][0][0] - 7.546738741619978) &lt; 1.e-12);
// <span style="color: #b22222;">(1,2,1)</span>
<span style="color: #0000ff;">assert</span>(fabs(<span style="color: #228b22;">en_distance</span>[0][0][1] - 8.77102435246984) &lt; 1.e-12);
// <span style="color: #b22222;">(2,1,1)</span>
<span style="color: #0000ff;">assert</span>(fabs(<span style="color: #228b22;">en_distance</span>[0][1][0] - 3.698922010513608) &lt; 1.e-12);
// <span style="color: #b22222;">(1,1,2)</span>
<span style="color: #0000ff;">assert</span>(fabs(<span style="color: #228b22;">en_distance</span>[1][0][0] - 5.824059436060509) &lt; 1.e-12);
// <span style="color: #b22222;">(1,2,2)</span>
<span style="color: #0000ff;">assert</span>(fabs(<span style="color: #228b22;">en_distance</span>[1][0][1] - 7.080482110317645) &lt; 1.e-12);
// <span style="color: #b22222;">(2,1,2)</span>
<span style="color: #0000ff;">assert</span>(fabs(<span style="color: #228b22;">en_distance</span>[1][1][0] - 3.1804527583077356) &lt; 1.e-12);
</pre>
</div>
</div>
</div>
</div>
<div id="outline-container-org8d56cf2" class="outline-3">
<h3 id="org8d56cf2"><span class="section-number-3">2.4</span> Electron-nucleus potential</h3>
<div class="outline-text-3" id="text-2-4">
<p>
<code>en_potential</code> stores the <code>en</code> potential energy
</p>
<p>
\[
\mathcal{V}_{en} = -\sum_{i=1}^{N_e}\sum_{A=1}^{N_n}\frac{Z_A}{r_{iA}}
\]
</p>
<p>
where \(\mathcal{V}_{en}\) is the <code>en</code> potential, \[r_{iA}\] the <code>en</code>
distance and \[Z_A\] is the nuclear charge.
</p>
</div>
<div id="outline-container-orgb431d98" class="outline-4">
<h4 id="orgb431d98"><span class="section-number-4">2.4.1</span> Get</h4>
<div class="outline-text-4" id="text-2-4-1">
<div class="org-src-container">
<pre class="src src-c"><span style="color: #228b22;">qmckl_exit_code</span> <span style="color: #0000ff;">qmckl_get_electron_en_potential</span>(<span style="color: #228b22;">qmckl_context</span> <span style="color: #a0522d;">context</span>, <span style="color: #228b22;">double</span>* <span style="color: #a020f0;">const</span> <span style="color: #a0522d;">en_potential</span>);
</pre>
</div>
</div>
</div>
<div id="outline-container-orgb0284b1" class="outline-4">
<h4 id="orgb0284b1"><span class="section-number-4">2.4.2</span> Compute</h4>
<div class="outline-text-4" id="text-2-4-2">
<table id="org1840074" border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides">
<colgroup>
<col class="org-left" />
<col class="org-left" />
<col class="org-left" />
<col class="org-left" />
</colgroup>
<thead>
<tr>
<th scope="col" class="org-left">Variable</th>
<th scope="col" class="org-left">Type</th>
<th scope="col" class="org-left">In/Out</th>
<th scope="col" class="org-left">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td class="org-left"><code>context</code></td>
<td class="org-left"><code>qmckl_context</code></td>
<td class="org-left">in</td>
<td class="org-left">Global state</td>
</tr>
<tr>
<td class="org-left"><code>elec_num</code></td>
<td class="org-left"><code>int64_t</code></td>
<td class="org-left">in</td>
<td class="org-left">Number of electrons</td>
</tr>
<tr>
<td class="org-left"><code>nucl_num</code></td>
<td class="org-left"><code>int64_t</code></td>
<td class="org-left">in</td>
<td class="org-left">Number of nuclei</td>
</tr>
<tr>
<td class="org-left"><code>walk_num</code></td>
<td class="org-left"><code>int64_t</code></td>
<td class="org-left">in</td>
<td class="org-left">Number of walkers</td>
</tr>
<tr>
<td class="org-left"><code>charge</code></td>
<td class="org-left"><code>double[nucl_num]</code></td>
<td class="org-left">in</td>
<td class="org-left">charge of nucleus</td>
</tr>
<tr>
<td class="org-left"><code>en_distance</code></td>
<td class="org-left"><code>double[walk_num][elec_num][nucl_num]</code></td>
<td class="org-left">in</td>
<td class="org-left">Electron-electron distances</td>
</tr>
<tr>
<td class="org-left"><code>en_potential</code></td>
<td class="org-left"><code>double[walk_num]</code></td>
<td class="org-left">out</td>
<td class="org-left">Electron-electron potential</td>
</tr>
</tbody>
</table>
<div class="org-src-container">
<pre class="src src-f90"><span style="color: #228b22;">integer</span><span style="color: #a0522d;"> function qmckl_compute_en_potential_f(context, elec_num, nucl_num, walk_num, </span><span style="color: #a020f0;">&amp;</span>
charge, en_distance, en_potential) <span style="color: #a020f0;">&amp;</span>
<span style="color: #a020f0;">result</span>(info)
<span style="color: #a020f0;">use</span> <span style="color: #0000ff;">qmckl</span>
<span style="color: #a020f0;">implicit</span> <span style="color: #228b22;">none</span>
<span style="color: #228b22;">integer</span>(qmckl_context), <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> context</span>
<span style="color: #228b22;">integer</span>*8 , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> elec_num</span>
<span style="color: #228b22;">integer</span>*8 , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> nucl_num</span>
<span style="color: #228b22;">integer</span>*8 , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> walk_num</span>
<span style="color: #228b22;">double precision</span> , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> charge(nucl_num)</span>
<span style="color: #228b22;">double precision</span> , <span style="color: #a020f0;">intent</span>(in) ::<span style="color: #a0522d;"> en_distance(nucl_num,elec_num,walk_num)</span>
<span style="color: #228b22;">double precision</span> , <span style="color: #a020f0;">intent</span>(out) ::<span style="color: #a0522d;"> en_potential(walk_num)</span>
<span style="color: #228b22;">integer</span>*8 ::<span style="color: #a0522d;"> nw, i, j</span>
info = QMCKL_SUCCESS
<span style="color: #a020f0;">if</span> (context == QMCKL_NULL_CONTEXT) <span style="color: #a020f0;">then</span>
info = QMCKL_INVALID_CONTEXT
<span style="color: #a020f0;">return</span>
<span style="color: #a020f0;">endif</span>
<span style="color: #a020f0;">if</span> (elec_num &lt;= 0) <span style="color: #a020f0;">then</span>
info = QMCKL_INVALID_ARG_2
<span style="color: #a020f0;">return</span>
<span style="color: #a020f0;">endif</span>
<span style="color: #a020f0;">if</span> (walk_num &lt;= 0) <span style="color: #a020f0;">then</span>
info = QMCKL_INVALID_ARG_3
<span style="color: #a020f0;">return</span>
<span style="color: #a020f0;">endif</span>
en_potential = 0.0d0
<span style="color: #a020f0;">do</span> nw=1,walk_num
<span style="color: #a020f0;">do</span> i=1,elec_num
<span style="color: #a020f0;">do</span> j=1,nucl_num
<span style="color: #a020f0;">if</span> (dabs(en_distance(j,i,nw)) &gt; 1.d-6) <span style="color: #a020f0;">then</span>
en_potential(nw) = en_potential(nw) - charge(j)/(en_distance(j,i,nw))
<span style="color: #a020f0;">endif</span>
<span style="color: #a020f0;">end do</span>
<span style="color: #a020f0;">end do</span>
<span style="color: #a020f0;">end do</span>
<span style="color: #a020f0;">end function</span> <span style="color: #0000ff;">qmckl_compute_en_potential_f</span>
</pre>
</div>
<div class="org-src-container">
<pre class="src src-c"><span style="color: #228b22;">qmckl_exit_code</span> <span style="color: #0000ff;">qmckl_compute_en_potential</span> (
<span style="color: #a020f0;">const</span> <span style="color: #228b22;">qmckl_context</span> <span style="color: #a0522d;">context</span>,
<span style="color: #a020f0;">const</span> <span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">elec_num</span>,
<span style="color: #a020f0;">const</span> <span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">nucl_num</span>,
<span style="color: #a020f0;">const</span> <span style="color: #228b22;">int64_t</span> <span style="color: #a0522d;">walk_num</span>,
<span style="color: #a020f0;">const</span> <span style="color: #228b22;">double</span>* <span style="color: #a0522d;">charge</span>,
<span style="color: #a020f0;">const</span> <span style="color: #228b22;">double</span>* <span style="color: #a0522d;">en_distance</span>,
<span style="color: #228b22;">double</span>* <span style="color: #a020f0;">const</span> <span style="color: #a0522d;">en_potential</span> );
</pre>
</div>
</div>
</div>
<div id="outline-container-org324f729" class="outline-4">
<h4 id="org324f729"><span class="section-number-4">2.4.3</span> Test</h4>
<div class="outline-text-4" id="text-2-4-3">
<div class="org-src-container">
<pre class="src src-c"><span style="color: #228b22;">double</span> <span style="color: #a0522d;">en_potential</span>[walk_num];
rc = qmckl_get_electron_en_potential(context, &amp;(en_potential[0]));
<span style="color: #0000ff;">qmckl_check</span>(context, rc);
</pre>
</div>
</div>
</div>
</div>
<div id="outline-container-org056cef2" class="outline-3">
<h3 id="org056cef2"><span class="section-number-3">2.5</span> Generate initial coordinates</h3>
</div>
</div>
</div>
<div id="postamble" class="status">
<p class="author">Author: TREX CoE</p>
<p class="date">Created: 2023-09-27 Wed 20:19</p>
<p class="validation"><a href="http://validator.w3.org/check?uri=referer">Validate</a></p>
</div>
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</html>