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<title>Quantum Monte Carlo</title> <title>Quantum Monte Carlo</title>
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<h2>Table of Contents</h2> <h2>Table of Contents</h2>
<div id="text-table-of-contents"> <div id="text-table-of-contents">
<ul> <ul>
<li><a href="#orgb186a8c">1. Introduction</a> <li><a href="#orge8bc398">1. Introduction</a>
<ul> <ul>
<li><a href="#org3c07f2e">1.1. Energy and local energy</a></li> <li><a href="#org706146e">1.1. Energy and local energy</a></li>
</ul> </ul>
</li> </li>
<li><a href="#org6c3768b">2. Numerical evaluation of the energy of the hydrogen atom</a> <li><a href="#org8eba34e">2. Numerical evaluation of the energy of the hydrogen atom</a>
<ul> <ul>
<li><a href="#org8d4f02a">2.1. Local energy</a> <li><a href="#orgb6798fe">2.1. Local energy</a>
<ul> <ul>
<li><a href="#org1591b12">2.1.1. Exercise 1</a> <li><a href="#org309f3a3">2.1.1. Exercise 1</a>
<ul> <ul>
<li><a href="#org29b9d1d">2.1.1.1. Solution</a></li> <li><a href="#orged35f0c">2.1.1.1. Solution</a></li>
</ul> </ul>
</li> </li>
<li><a href="#orgf12e1c4">2.1.2. Exercise 2</a> <li><a href="#org9cb5b69">2.1.2. Exercise 2</a>
<ul> <ul>
<li><a href="#orgacd2ba7">2.1.2.1. Solution</a></li> <li><a href="#org9650566">2.1.2.1. Solution</a></li>
</ul> </ul>
</li> </li>
<li><a href="#org888cf22">2.1.3. Exercise 3</a> <li><a href="#org3c48519">2.1.3. Exercise 3</a>
<ul> <ul>
<li><a href="#org30fb55d">2.1.3.1. Solution</a></li> <li><a href="#org705631c">2.1.3.1. Solution</a></li>
</ul> </ul>
</li> </li>
<li><a href="#org5a00a8e">2.1.4. Exercise 4</a> <li><a href="#orgd94ed87">2.1.4. Exercise 4</a>
<ul> <ul>
<li><a href="#org2faf37d">2.1.4.1. Solution</a></li> <li><a href="#orgd9baa77">2.1.4.1. Solution</a></li>
</ul> </ul>
</li> </li>
<li><a href="#org0056e00">2.1.5. Exercise 5</a> <li><a href="#orgd1d6cba">2.1.5. Exercise 5</a>
<ul> <ul>
<li><a href="#org783b0a8">2.1.5.1. Solution</a></li> <li><a href="#org6c2caf1">2.1.5.1. Solution</a></li>
</ul> </ul>
</li> </li>
</ul> </ul>
</li> </li>
<li><a href="#org311b3ff">2.2. Plot of the local energy along the \(x\) axis</a> <li><a href="#orgf3480bd">2.2. Plot of the local energy along the \(x\) axis</a>
<ul> <ul>
<li><a href="#org46306e2">2.2.1. Exercise</a> <li><a href="#org75d9a33">2.2.1. Exercise</a>
<ul> <ul>
<li><a href="#org9e51c10">2.2.1.1. Solution</a></li> <li><a href="#orgb512433">2.2.1.1. Solution</a></li>
</ul> </ul>
</li> </li>
</ul> </ul>
</li> </li>
<li><a href="#org72e84b0">2.3. Numerical estimation of the energy</a> <li><a href="#orgd8457b5">2.3. Numerical estimation of the energy</a>
<ul> <ul>
<li><a href="#org186fca9">2.3.1. Exercise</a> <li><a href="#orgd00b45f">2.3.1. Exercise</a>
<ul> <ul>
<li><a href="#org8cb189b">2.3.1.1. Solution</a></li> <li><a href="#org8ef4dfd">2.3.1.1. Solution</a></li>
</ul> </ul>
</li> </li>
</ul> </ul>
</li> </li>
<li><a href="#org1f533db">2.4. Variance of the local energy</a> <li><a href="#org54576bb">2.4. Variance of the local energy</a>
<ul> <ul>
<li><a href="#org1c12076">2.4.1. Exercise (optional)</a> <li><a href="#org77249ac">2.4.1. Exercise (optional)</a>
<ul> <ul>
<li><a href="#orgddc9796">2.4.1.1. Solution</a></li> <li><a href="#org229d0cf">2.4.1.1. Solution</a></li>
</ul> </ul>
</li> </li>
<li><a href="#org208f015">2.4.2. Exercise</a> <li><a href="#orga7192e3">2.4.2. Exercise</a>
<ul> <ul>
<li><a href="#org0ba92f9">2.4.2.1. Solution</a></li> <li><a href="#org6ffe540">2.4.2.1. Solution</a></li>
</ul> </ul>
</li> </li>
</ul> </ul>
</li> </li>
</ul> </ul>
</li> </li>
<li><a href="#org5ae1ab3">3. Variational Monte Carlo</a> <li><a href="#org7c5ed18">3. Variational Monte Carlo</a>
<ul> <ul>
<li><a href="#org5300922">3.1. Computation of the statistical error</a> <li><a href="#orgbd75310">3.1. Computation of the statistical error</a>
<ul> <ul>
<li><a href="#orga3239e0">3.1.1. Exercise</a> <li><a href="#org776529e">3.1.1. Exercise</a>
<ul> <ul>
<li><a href="#orgfd9f832">3.1.1.1. Solution</a></li> <li><a href="#orgd623403">3.1.1.1. Solution</a></li>
</ul> </ul>
</li> </li>
</ul> </ul>
</li> </li>
<li><a href="#org4c87384">3.2. Uniform sampling in the box</a> <li><a href="#orged02a3d">3.2. Uniform sampling in the box</a>
<ul> <ul>
<li><a href="#org105ca78">3.2.1. Exercise</a> <li><a href="#orgafe912c">3.2.1. Exercise</a>
<ul> <ul>
<li><a href="#orgd77ca5f">3.2.1.1. Solution</a></li> <li><a href="#org6d2da6a">3.2.1.1. Solution</a></li>
</ul> </ul>
</li> </li>
</ul> </ul>
</li> </li>
<li><a href="#orgb680fad">3.3. Metropolis sampling with \(\Psi^2\)</a> <li><a href="#org24dd766">3.3. Metropolis sampling with \(\Psi^2\)</a>
<ul> <ul>
<li><a href="#org6ef8716">3.3.1. Exercise</a> <li><a href="#org38a53b5">3.3.1. Exercise</a>
<ul> <ul>
<li><a href="#org2733db3">3.3.1.1. Solution</a></li> <li><a href="#org0478678">3.3.1.1. Solution</a></li>
</ul> </ul>
</li> </li>
</ul> </ul>
</li> </li>
<li><a href="#org672d772">3.4. Gaussian random number generator</a></li> <li><a href="#org9fbaf17">3.4. Gaussian random number generator</a></li>
<li><a href="#org81ee444">3.5. Generalized Metropolis algorithm</a> <li><a href="#org157d686">3.5. Generalized Metropolis algorithm</a>
<ul> <ul>
<li><a href="#org6c3fd5c">3.5.1. Exercise 1</a> <li><a href="#org664cd9b">3.5.1. Exercise 1</a>
<ul> <ul>
<li><a href="#orgba0ac9a">3.5.1.1. Solution</a></li> <li><a href="#org5e7f9b6">3.5.1.1. Solution</a></li>
</ul> </ul>
</li> </li>
<li><a href="#org44736e6">3.5.2. Exercise 2</a> <li><a href="#org7fc8051">3.5.2. Exercise 2</a>
<ul> <ul>
<li><a href="#org7f027dd">3.5.2.1. Solution</a></li> <li><a href="#orgf51edc7">3.5.2.1. Solution</a></li>
</ul> </ul>
</li> </li>
</ul> </ul>
</li> </li>
</ul> </ul>
</li> </li>
<li><a href="#orgd0f0196">4. Diffusion Monte Carlo</a> <li><a href="#org05f3f4f">4. Diffusion Monte Carlo</a>
<ul> <ul>
<li><a href="#org45a6987">4.1. Schrödinger equation in imaginary time</a></li> <li><a href="#org2360326">4.1. Schrödinger equation in imaginary time</a></li>
<li><a href="#org7b75ae2">4.2. Diffusion and branching</a></li> <li><a href="#org269a713">4.2. Diffusion and branching</a></li>
<li><a href="#orge14c674">4.3. Importance sampling</a> <li><a href="#org420b954">4.3. Importance sampling</a>
<ul> <ul>
<li><a href="#org872eba8">4.3.1. Appendix : Details of the Derivation</a></li> <li><a href="#org24db661">4.3.1. Appendix : Details of the Derivation</a></li>
</ul> </ul>
</li> </li>
<li><a href="#org2d4e0bf">4.4. Fixed-node DMC energy</a></li> <li><a href="#org5d1b87c">4.4. Pure Diffusion Monte Carlo (PDMC)</a></li>
<li><a href="#org53f374e">4.5. Pure Diffusion Monte Carlo (PDMC)</a></li> <li><a href="#org8fce010">4.5. Hydrogen atom</a>
<li><a href="#org9a97445">4.6. Hydrogen atom</a>
<ul> <ul>
<li><a href="#org3ed78fd">4.6.1. Exercise</a> <li><a href="#org1ae20b2">4.5.1. Exercise</a>
<ul> <ul>
<li><a href="#org2e9047d">4.6.1.1. Solution</a></li> <li><a href="#orgd9f1564">4.5.1.1. Solution</a></li>
</ul> </ul>
</li> </li>
</ul> </ul>
</li> </li>
<li><a href="#org5f489b3">4.7. <span class="todo TODO">TODO</span> H<sub>2</sub></a></li> <li><a href="#org711f9e1">4.6. <span class="todo TODO">TODO</span> H<sub>2</sub></a></li>
</ul> </ul>
</li> </li>
<li><a href="#org2330d12">5. <span class="todo TODO">TODO</span> <code>[0/3]</code> Last things to do</a></li> <li><a href="#org4874bf9">5. <span class="todo TODO">TODO</span> <code>[0/3]</code> Last things to do</a></li>
</ul> </ul>
</div> </div>
</div> </div>
<div id="outline-container-orgb186a8c" class="outline-2"> <div id="outline-container-orge8bc398" class="outline-2">
<h2 id="orgb186a8c"><span class="section-number-2">1</span> Introduction</h2> <h2 id="orge8bc398"><span class="section-number-2">1</span> Introduction</h2>
<div class="outline-text-2" id="text-1"> <div class="outline-text-2" id="text-1">
<p> <p>
This website contains the QMC tutorial of the 2021 LTTC winter school This website contains the QMC tutorial of the 2021 LTTC winter school
@ -514,8 +513,8 @@ coordinates, etc).
</p> </p>
</div> </div>
<div id="outline-container-org3c07f2e" class="outline-3"> <div id="outline-container-org706146e" class="outline-3">
<h3 id="org3c07f2e"><span class="section-number-3">1.1</span> Energy and local energy</h3> <h3 id="org706146e"><span class="section-number-3">1.1</span> Energy and local energy</h3>
<div class="outline-text-3" id="text-1-1"> <div class="outline-text-3" id="text-1-1">
<p> <p>
For a given system with Hamiltonian \(\hat{H}\) and wave function \(\Psi\), we define the local energy as For a given system with Hamiltonian \(\hat{H}\) and wave function \(\Psi\), we define the local energy as
@ -593,8 +592,8 @@ $$ E &asymp; \frac{1}{N<sub>\rm MC</sub>} &sum;<sub>i=1</sub><sup>N<sub>\rm MC</
</div> </div>
</div> </div>
<div id="outline-container-org6c3768b" class="outline-2"> <div id="outline-container-org8eba34e" class="outline-2">
<h2 id="org6c3768b"><span class="section-number-2">2</span> Numerical evaluation of the energy of the hydrogen atom</h2> <h2 id="org8eba34e"><span class="section-number-2">2</span> Numerical evaluation of the energy of the hydrogen atom</h2>
<div class="outline-text-2" id="text-2"> <div class="outline-text-2" id="text-2">
<p> <p>
In this section, we consider the hydrogen atom with the following In this section, we consider the hydrogen atom with the following
@ -623,8 +622,8 @@ To do that, we will compute the local energy and check whether it is constant.
</p> </p>
</div> </div>
<div id="outline-container-org8d4f02a" class="outline-3"> <div id="outline-container-orgb6798fe" class="outline-3">
<h3 id="org8d4f02a"><span class="section-number-3">2.1</span> Local energy</h3> <h3 id="orgb6798fe"><span class="section-number-3">2.1</span> Local energy</h3>
<div class="outline-text-3" id="text-2-1"> <div class="outline-text-3" id="text-2-1">
<p> <p>
You will now program all quantities needed to compute the local energy of the H atom for the given wave function. You will now program all quantities needed to compute the local energy of the H atom for the given wave function.
@ -651,8 +650,8 @@ to catch the error.
</div> </div>
</div> </div>
<div id="outline-container-org1591b12" class="outline-4"> <div id="outline-container-org309f3a3" class="outline-4">
<h4 id="org1591b12"><span class="section-number-4">2.1.1</span> Exercise 1</h4> <h4 id="org309f3a3"><span class="section-number-4">2.1.1</span> Exercise 1</h4>
<div class="outline-text-4" id="text-2-1-1"> <div class="outline-text-4" id="text-2-1-1">
<div class="exercise"> <div class="exercise">
<p> <p>
@ -696,8 +695,8 @@ and returns the potential.
</div> </div>
</div> </div>
<div id="outline-container-org29b9d1d" class="outline-5"> <div id="outline-container-orged35f0c" class="outline-5">
<h5 id="org29b9d1d"><span class="section-number-5">2.1.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5> <h5 id="orged35f0c"><span class="section-number-5">2.1.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5>
<div class="outline-text-5" id="text-2-1-1-1"> <div class="outline-text-5" id="text-2-1-1-1">
<p> <p>
<b>Python</b> <b>Python</b>
@ -737,8 +736,8 @@ and returns the potential.
</div> </div>
</div> </div>
<div id="outline-container-orgf12e1c4" class="outline-4"> <div id="outline-container-org9cb5b69" class="outline-4">
<h4 id="orgf12e1c4"><span class="section-number-4">2.1.2</span> Exercise 2</h4> <h4 id="org9cb5b69"><span class="section-number-4">2.1.2</span> Exercise 2</h4>
<div class="outline-text-4" id="text-2-1-2"> <div class="outline-text-4" id="text-2-1-2">
<div class="exercise"> <div class="exercise">
<p> <p>
@ -773,8 +772,8 @@ input arguments, and returns a scalar.
</div> </div>
</div> </div>
<div id="outline-container-orgacd2ba7" class="outline-5"> <div id="outline-container-org9650566" class="outline-5">
<h5 id="orgacd2ba7"><span class="section-number-5">2.1.2.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5> <h5 id="org9650566"><span class="section-number-5">2.1.2.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5>
<div class="outline-text-5" id="text-2-1-2-1"> <div class="outline-text-5" id="text-2-1-2-1">
<p> <p>
<b>Python</b> <b>Python</b>
@ -801,8 +800,8 @@ input arguments, and returns a scalar.
</div> </div>
</div> </div>
<div id="outline-container-org888cf22" class="outline-4"> <div id="outline-container-org3c48519" class="outline-4">
<h4 id="org888cf22"><span class="section-number-4">2.1.3</span> Exercise 3</h4> <h4 id="org3c48519"><span class="section-number-4">2.1.3</span> Exercise 3</h4>
<div class="outline-text-4" id="text-2-1-3"> <div class="outline-text-4" id="text-2-1-3">
<div class="exercise"> <div class="exercise">
<p> <p>
@ -883,8 +882,8 @@ Therefore, the local kinetic energy is
</div> </div>
</div> </div>
<div id="outline-container-org30fb55d" class="outline-5"> <div id="outline-container-org705631c" class="outline-5">
<h5 id="org30fb55d"><span class="section-number-5">2.1.3.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5> <h5 id="org705631c"><span class="section-number-5">2.1.3.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5>
<div class="outline-text-5" id="text-2-1-3-1"> <div class="outline-text-5" id="text-2-1-3-1">
<p> <p>
<b>Python</b> <b>Python</b>
@ -925,8 +924,8 @@ Therefore, the local kinetic energy is
</div> </div>
</div> </div>
<div id="outline-container-org5a00a8e" class="outline-4"> <div id="outline-container-orgd94ed87" class="outline-4">
<h4 id="org5a00a8e"><span class="section-number-4">2.1.4</span> Exercise 4</h4> <h4 id="orgd94ed87"><span class="section-number-4">2.1.4</span> Exercise 4</h4>
<div class="outline-text-4" id="text-2-1-4"> <div class="outline-text-4" id="text-2-1-4">
<div class="exercise"> <div class="exercise">
<p> <p>
@ -969,8 +968,8 @@ local kinetic energy.
</div> </div>
</div> </div>
<div id="outline-container-org2faf37d" class="outline-5"> <div id="outline-container-orgd9baa77" class="outline-5">
<h5 id="org2faf37d"><span class="section-number-5">2.1.4.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5> <h5 id="orgd9baa77"><span class="section-number-5">2.1.4.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5>
<div class="outline-text-5" id="text-2-1-4-1"> <div class="outline-text-5" id="text-2-1-4-1">
<p> <p>
<b>Python</b> <b>Python</b>
@ -1000,8 +999,8 @@ local kinetic energy.
</div> </div>
</div> </div>
<div id="outline-container-org0056e00" class="outline-4"> <div id="outline-container-orgd1d6cba" class="outline-4">
<h4 id="org0056e00"><span class="section-number-4">2.1.5</span> Exercise 5</h4> <h4 id="orgd1d6cba"><span class="section-number-4">2.1.5</span> Exercise 5</h4>
<div class="outline-text-4" id="text-2-1-5"> <div class="outline-text-4" id="text-2-1-5">
<div class="exercise"> <div class="exercise">
<p> <p>
@ -1011,8 +1010,8 @@ Find the theoretical value of \(a\) for which \(\Psi\) is an eigenfunction of \(
</div> </div>
</div> </div>
<div id="outline-container-org783b0a8" class="outline-5"> <div id="outline-container-org6c2caf1" class="outline-5">
<h5 id="org783b0a8"><span class="section-number-5">2.1.5.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5> <h5 id="org6c2caf1"><span class="section-number-5">2.1.5.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5>
<div class="outline-text-5" id="text-2-1-5-1"> <div class="outline-text-5" id="text-2-1-5-1">
\begin{eqnarray*} \begin{eqnarray*}
E &=& \frac{\hat{H} \Psi}{\Psi} = - \frac{1}{2} \frac{\Delta \Psi}{\Psi} - E &=& \frac{\hat{H} \Psi}{\Psi} = - \frac{1}{2} \frac{\Delta \Psi}{\Psi} -
@ -1032,8 +1031,8 @@ equal to -0.5 atomic units.
</div> </div>
</div> </div>
<div id="outline-container-org311b3ff" class="outline-3"> <div id="outline-container-orgf3480bd" class="outline-3">
<h3 id="org311b3ff"><span class="section-number-3">2.2</span> Plot of the local energy along the \(x\) axis</h3> <h3 id="orgf3480bd"><span class="section-number-3">2.2</span> Plot of the local energy along the \(x\) axis</h3>
<div class="outline-text-3" id="text-2-2"> <div class="outline-text-3" id="text-2-2">
<div class="note"> <div class="note">
<p> <p>
@ -1044,8 +1043,8 @@ choose a grid which does not contain the origin.
</div> </div>
</div> </div>
<div id="outline-container-org46306e2" class="outline-4"> <div id="outline-container-org75d9a33" class="outline-4">
<h4 id="org46306e2"><span class="section-number-4">2.2.1</span> Exercise</h4> <h4 id="org75d9a33"><span class="section-number-4">2.2.1</span> Exercise</h4>
<div class="outline-text-4" id="text-2-2-1"> <div class="outline-text-4" id="text-2-2-1">
<div class="exercise"> <div class="exercise">
<p> <p>
@ -1128,8 +1127,8 @@ plot './data' index 0 using 1:2 with lines title 'a=0.1', \
</div> </div>
</div> </div>
<div id="outline-container-org9e51c10" class="outline-5"> <div id="outline-container-orgb512433" class="outline-5">
<h5 id="org9e51c10"><span class="section-number-5">2.2.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5> <h5 id="orgb512433"><span class="section-number-5">2.2.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5>
<div class="outline-text-5" id="text-2-2-1-1"> <div class="outline-text-5" id="text-2-2-1-1">
<p> <p>
<b>Python</b> <b>Python</b>
@ -1204,8 +1203,8 @@ plt.savefig(<span style="color: #8b2252;">"plot_py.png"</span>)
</div> </div>
</div> </div>
<div id="outline-container-org72e84b0" class="outline-3"> <div id="outline-container-orgd8457b5" class="outline-3">
<h3 id="org72e84b0"><span class="section-number-3">2.3</span> Numerical estimation of the energy</h3> <h3 id="orgd8457b5"><span class="section-number-3">2.3</span> Numerical estimation of the energy</h3>
<div class="outline-text-3" id="text-2-3"> <div class="outline-text-3" id="text-2-3">
<p> <p>
If the space is discretized in small volume elements \(\mathbf{r}_i\) If the space is discretized in small volume elements \(\mathbf{r}_i\)
@ -1235,8 +1234,8 @@ The energy is biased because:
</div> </div>
<div id="outline-container-org186fca9" class="outline-4"> <div id="outline-container-orgd00b45f" class="outline-4">
<h4 id="org186fca9"><span class="section-number-4">2.3.1</span> Exercise</h4> <h4 id="orgd00b45f"><span class="section-number-4">2.3.1</span> Exercise</h4>
<div class="outline-text-4" id="text-2-3-1"> <div class="outline-text-4" id="text-2-3-1">
<div class="exercise"> <div class="exercise">
<p> <p>
@ -1305,8 +1304,8 @@ To compile the Fortran and run it:
</div> </div>
</div> </div>
<div id="outline-container-org8cb189b" class="outline-5"> <div id="outline-container-org8ef4dfd" class="outline-5">
<h5 id="org8cb189b"><span class="section-number-5">2.3.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5> <h5 id="org8ef4dfd"><span class="section-number-5">2.3.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5>
<div class="outline-text-5" id="text-2-3-1-1"> <div class="outline-text-5" id="text-2-3-1-1">
<p> <p>
<b>Python</b> <b>Python</b>
@ -1421,8 +1420,8 @@ a = 2.0000000000000000 E = -8.0869806678448772E-002
</div> </div>
</div> </div>
<div id="outline-container-org1f533db" class="outline-3"> <div id="outline-container-org54576bb" class="outline-3">
<h3 id="org1f533db"><span class="section-number-3">2.4</span> Variance of the local energy</h3> <h3 id="org54576bb"><span class="section-number-3">2.4</span> Variance of the local energy</h3>
<div class="outline-text-3" id="text-2-4"> <div class="outline-text-3" id="text-2-4">
<p> <p>
The variance of the local energy is a functional of \(\Psi\) The variance of the local energy is a functional of \(\Psi\)
@ -1449,8 +1448,8 @@ energy can be used as a measure of the quality of a wave function.
</p> </p>
</div> </div>
<div id="outline-container-org1c12076" class="outline-4"> <div id="outline-container-org77249ac" class="outline-4">
<h4 id="org1c12076"><span class="section-number-4">2.4.1</span> Exercise (optional)</h4> <h4 id="org77249ac"><span class="section-number-4">2.4.1</span> Exercise (optional)</h4>
<div class="outline-text-4" id="text-2-4-1"> <div class="outline-text-4" id="text-2-4-1">
<div class="exercise"> <div class="exercise">
<p> <p>
@ -1461,8 +1460,8 @@ Prove that :
</div> </div>
</div> </div>
<div id="outline-container-orgddc9796" class="outline-5"> <div id="outline-container-org229d0cf" class="outline-5">
<h5 id="orgddc9796"><span class="section-number-5">2.4.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5> <h5 id="org229d0cf"><span class="section-number-5">2.4.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5>
<div class="outline-text-5" id="text-2-4-1-1"> <div class="outline-text-5" id="text-2-4-1-1">
<p> <p>
\(\bar{E} = \langle E \rangle\) is a constant, so \(\langle \bar{E} \(\bar{E} = \langle E \rangle\) is a constant, so \(\langle \bar{E}
@ -1481,8 +1480,8 @@ Prove that :
</div> </div>
</div> </div>
</div> </div>
<div id="outline-container-org208f015" class="outline-4"> <div id="outline-container-orga7192e3" class="outline-4">
<h4 id="org208f015"><span class="section-number-4">2.4.2</span> Exercise</h4> <h4 id="orga7192e3"><span class="section-number-4">2.4.2</span> Exercise</h4>
<div class="outline-text-4" id="text-2-4-2"> <div class="outline-text-4" id="text-2-4-2">
<div class="exercise"> <div class="exercise">
<p> <p>
@ -1556,8 +1555,8 @@ To compile and run:
</div> </div>
</div> </div>
<div id="outline-container-org0ba92f9" class="outline-5"> <div id="outline-container-org6ffe540" class="outline-5">
<h5 id="org0ba92f9"><span class="section-number-5">2.4.2.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5> <h5 id="org6ffe540"><span class="section-number-5">2.4.2.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5>
<div class="outline-text-5" id="text-2-4-2-1"> <div class="outline-text-5" id="text-2-4-2-1">
<p> <p>
<b>Python</b> <b>Python</b>
@ -1694,8 +1693,8 @@ a = 2.0000000000000000 E = -8.0869806678448772E-002 s2 = 1.8068814
</div> </div>
</div> </div>
<div id="outline-container-org5ae1ab3" class="outline-2"> <div id="outline-container-org7c5ed18" class="outline-2">
<h2 id="org5ae1ab3"><span class="section-number-2">3</span> Variational Monte Carlo</h2> <h2 id="org7c5ed18"><span class="section-number-2">3</span> Variational Monte Carlo</h2>
<div class="outline-text-2" id="text-3"> <div class="outline-text-2" id="text-3">
<p> <p>
Numerical integration with deterministic methods is very efficient Numerical integration with deterministic methods is very efficient
@ -1711,8 +1710,8 @@ interval.
</p> </p>
</div> </div>
<div id="outline-container-org5300922" class="outline-3"> <div id="outline-container-orgbd75310" class="outline-3">
<h3 id="org5300922"><span class="section-number-3">3.1</span> Computation of the statistical error</h3> <h3 id="orgbd75310"><span class="section-number-3">3.1</span> Computation of the statistical error</h3>
<div class="outline-text-3" id="text-3-1"> <div class="outline-text-3" id="text-3-1">
<p> <p>
To compute the statistical error, you need to perform \(M\) To compute the statistical error, you need to perform \(M\)
@ -1752,8 +1751,8 @@ And the confidence interval is given by
</p> </p>
</div> </div>
<div id="outline-container-orga3239e0" class="outline-4"> <div id="outline-container-org776529e" class="outline-4">
<h4 id="orga3239e0"><span class="section-number-4">3.1.1</span> Exercise</h4> <h4 id="org776529e"><span class="section-number-4">3.1.1</span> Exercise</h4>
<div class="outline-text-4" id="text-3-1-1"> <div class="outline-text-4" id="text-3-1-1">
<div class="exercise"> <div class="exercise">
<p> <p>
@ -1791,8 +1790,8 @@ input array.
</div> </div>
</div> </div>
<div id="outline-container-orgfd9f832" class="outline-5"> <div id="outline-container-orgd623403" class="outline-5">
<h5 id="orgfd9f832"><span class="section-number-5">3.1.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5> <h5 id="orgd623403"><span class="section-number-5">3.1.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5>
<div class="outline-text-5" id="text-3-1-1-1"> <div class="outline-text-5" id="text-3-1-1-1">
<p> <p>
<b>Python</b> <b>Python</b>
@ -1851,8 +1850,8 @@ input array.
</div> </div>
</div> </div>
<div id="outline-container-org4c87384" class="outline-3"> <div id="outline-container-orged02a3d" class="outline-3">
<h3 id="org4c87384"><span class="section-number-3">3.2</span> Uniform sampling in the box</h3> <h3 id="orged02a3d"><span class="section-number-3">3.2</span> Uniform sampling in the box</h3>
<div class="outline-text-3" id="text-3-2"> <div class="outline-text-3" id="text-3-2">
<p> <p>
We will now perform our first Monte Carlo calculation to compute the We will now perform our first Monte Carlo calculation to compute the
@ -1913,8 +1912,8 @@ compute the statistical error.
</p> </p>
</div> </div>
<div id="outline-container-org105ca78" class="outline-4"> <div id="outline-container-orgafe912c" class="outline-4">
<h4 id="org105ca78"><span class="section-number-4">3.2.1</span> Exercise</h4> <h4 id="orgafe912c"><span class="section-number-4">3.2.1</span> Exercise</h4>
<div class="outline-text-4" id="text-3-2-1"> <div class="outline-text-4" id="text-3-2-1">
<div class="exercise"> <div class="exercise">
<p> <p>
@ -2014,8 +2013,8 @@ well as the index of the current step.
</div> </div>
</div> </div>
<div id="outline-container-orgd77ca5f" class="outline-5"> <div id="outline-container-org6d2da6a" class="outline-5">
<h5 id="orgd77ca5f"><span class="section-number-5">3.2.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5> <h5 id="org6d2da6a"><span class="section-number-5">3.2.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5>
<div class="outline-text-5" id="text-3-2-1-1"> <div class="outline-text-5" id="text-3-2-1-1">
<p> <p>
<b>Python</b> <b>Python</b>
@ -2129,8 +2128,8 @@ E = -0.49518773675598715 +/- 5.2391494923686175E-004
</div> </div>
</div> </div>
<div id="outline-container-orgb680fad" class="outline-3"> <div id="outline-container-org24dd766" class="outline-3">
<h3 id="orgb680fad"><span class="section-number-3">3.3</span> Metropolis sampling with \(\Psi^2\)</h3> <h3 id="org24dd766"><span class="section-number-3">3.3</span> Metropolis sampling with \(\Psi^2\)</h3>
<div class="outline-text-3" id="text-3-3"> <div class="outline-text-3" id="text-3-3">
<p> <p>
We will now use the square of the wave function to sample random We will now use the square of the wave function to sample random
@ -2263,14 +2262,14 @@ compromise for the current problem.
</p> </p>
<p> <p>
NOTE: below, we use the symbol dt for dL for reasons which will NOTE: below, we use the symbol dt to denote dL since we will use
become clear later. the same variable later on to store a time step.
</p> </p>
</div> </div>
<div id="outline-container-org6ef8716" class="outline-4"> <div id="outline-container-org38a53b5" class="outline-4">
<h4 id="org6ef8716"><span class="section-number-4">3.3.1</span> Exercise</h4> <h4 id="org38a53b5"><span class="section-number-4">3.3.1</span> Exercise</h4>
<div class="outline-text-4" id="text-3-3-1"> <div class="outline-text-4" id="text-3-3-1">
<div class="exercise"> <div class="exercise">
<p> <p>
@ -2377,8 +2376,8 @@ Can you observe a reduction in the statistical error?
</div> </div>
</div> </div>
<div id="outline-container-org2733db3" class="outline-5"> <div id="outline-container-org0478678" class="outline-5">
<h5 id="org2733db3"><span class="section-number-5">3.3.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5> <h5 id="org0478678"><span class="section-number-5">3.3.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5>
<div class="outline-text-5" id="text-3-3-1-1"> <div class="outline-text-5" id="text-3-3-1-1">
<p> <p>
<b>Python</b> <b>Python</b>
@ -2523,8 +2522,8 @@ A = 0.51695266666666673 +/- 4.0445505648997396E-004
</div> </div>
</div> </div>
<div id="outline-container-org672d772" class="outline-3"> <div id="outline-container-org9fbaf17" class="outline-3">
<h3 id="org672d772"><span class="section-number-3">3.4</span> Gaussian random number generator</h3> <h3 id="org9fbaf17"><span class="section-number-3">3.4</span> Gaussian random number generator</h3>
<div class="outline-text-3" id="text-3-4"> <div class="outline-text-3" id="text-3-4">
<p> <p>
To obtain Gaussian-distributed random numbers, you can apply the To obtain Gaussian-distributed random numbers, you can apply the
@ -2587,8 +2586,8 @@ In Python, you can use the <a href="https://numpy.org/doc/stable/reference/rando
</div> </div>
</div> </div>
<div id="outline-container-org81ee444" class="outline-3"> <div id="outline-container-org157d686" class="outline-3">
<h3 id="org81ee444"><span class="section-number-3">3.5</span> Generalized Metropolis algorithm</h3> <h3 id="org157d686"><span class="section-number-3">3.5</span> Generalized Metropolis algorithm</h3>
<div class="outline-text-3" id="text-3-5"> <div class="outline-text-3" id="text-3-5">
<p> <p>
One can use more efficient numerical schemes to move the electrons by choosing a smarter expression for the transition probability. One can use more efficient numerical schemes to move the electrons by choosing a smarter expression for the transition probability.
@ -2720,8 +2719,8 @@ Evaluate \(\Psi\) and \(\frac{\nabla \Psi(\mathbf{r})}{\Psi(\mathbf{r})}\) at th
</div> </div>
<div id="outline-container-org6c3fd5c" class="outline-4"> <div id="outline-container-org664cd9b" class="outline-4">
<h4 id="org6c3fd5c"><span class="section-number-4">3.5.1</span> Exercise 1</h4> <h4 id="org664cd9b"><span class="section-number-4">3.5.1</span> Exercise 1</h4>
<div class="outline-text-4" id="text-3-5-1"> <div class="outline-text-4" id="text-3-5-1">
<div class="exercise"> <div class="exercise">
<p> <p>
@ -2755,8 +2754,8 @@ Write a function to compute the drift vector \(\frac{\nabla \Psi(\mathbf{r})}{\P
</div> </div>
</div> </div>
<div id="outline-container-orgba0ac9a" class="outline-5"> <div id="outline-container-org5e7f9b6" class="outline-5">
<h5 id="orgba0ac9a"><span class="section-number-5">3.5.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5> <h5 id="org5e7f9b6"><span class="section-number-5">3.5.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5>
<div class="outline-text-5" id="text-3-5-1-1"> <div class="outline-text-5" id="text-3-5-1-1">
<p> <p>
<b>Python</b> <b>Python</b>
@ -2789,8 +2788,8 @@ Write a function to compute the drift vector \(\frac{\nabla \Psi(\mathbf{r})}{\P
</div> </div>
</div> </div>
<div id="outline-container-org44736e6" class="outline-4"> <div id="outline-container-org7fc8051" class="outline-4">
<h4 id="org44736e6"><span class="section-number-4">3.5.2</span> Exercise 2</h4> <h4 id="org7fc8051"><span class="section-number-4">3.5.2</span> Exercise 2</h4>
<div class="outline-text-4" id="text-3-5-2"> <div class="outline-text-4" id="text-3-5-2">
<div class="exercise"> <div class="exercise">
<p> <p>
@ -2884,8 +2883,8 @@ Modify the previous program to introduce the drift-diffusion scheme.
</div> </div>
</div> </div>
<div id="outline-container-org7f027dd" class="outline-5"> <div id="outline-container-orgf51edc7" class="outline-5">
<h5 id="org7f027dd"><span class="section-number-5">3.5.2.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5> <h5 id="orgf51edc7"><span class="section-number-5">3.5.2.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5>
<div class="outline-text-5" id="text-3-5-2-1"> <div class="outline-text-5" id="text-3-5-2-1">
<p> <p>
<b>Python</b> <b>Python</b>
@ -3071,12 +3070,12 @@ A = 0.78839866666666658 +/- 3.2503783452043152E-004
</div> </div>
</div> </div>
<div id="outline-container-orgd0f0196" class="outline-2"> <div id="outline-container-org05f3f4f" class="outline-2">
<h2 id="orgd0f0196"><span class="section-number-2">4</span> Diffusion Monte Carlo&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h2> <h2 id="org05f3f4f"><span class="section-number-2">4</span> Diffusion Monte Carlo&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h2>
<div class="outline-text-2" id="text-4"> <div class="outline-text-2" id="text-4">
</div> </div>
<div id="outline-container-org45a6987" class="outline-3"> <div id="outline-container-org2360326" class="outline-3">
<h3 id="org45a6987"><span class="section-number-3">4.1</span> Schrödinger equation in imaginary time</h3> <h3 id="org2360326"><span class="section-number-3">4.1</span> Schrödinger equation in imaginary time</h3>
<div class="outline-text-3" id="text-4-1"> <div class="outline-text-3" id="text-4-1">
<p> <p>
Consider the time-dependent Schrödinger equation: Consider the time-dependent Schrödinger equation:
@ -3144,8 +3143,8 @@ system.
</div> </div>
</div> </div>
<div id="outline-container-org7b75ae2" class="outline-3"> <div id="outline-container-org269a713" class="outline-3">
<h3 id="org7b75ae2"><span class="section-number-3">4.2</span> Diffusion and branching</h3> <h3 id="org269a713"><span class="section-number-3">4.2</span> Diffusion and branching</h3>
<div class="outline-text-3" id="text-4-2"> <div class="outline-text-3" id="text-4-2">
<p> <p>
The imaginary-time Schrödinger equation can be explicitly written in terms of the kinetic and The imaginary-time Schrödinger equation can be explicitly written in terms of the kinetic and
@ -3220,18 +3219,33 @@ the combination of a diffusion process and a branching process.
</p> </p>
<p> <p>
We note here that the ground-state wave function of a Fermionic system is We note that the ground-state wave function of a Fermionic system is
antisymmetric and changes sign. antisymmetric and changes sign. Therefore, it is interpretation as a probability
distribution is somewhat problematic. In fact, mathematically, since
the Bosonic ground state is lower in energy than the Fermionic one, for
large \(\tau\), the system will evolve towards the Bosonic solution.
</p> </p>
<p> <p>
I AM HERE For the systems you will study this is not an issue:
</p>
<ul class="org-ul">
<li>Hydrogen atom: You only have one electron!</li>
<li>Two-electron system (\(H_2\) or He): The ground-wave function is antisymmetric</li>
</ul>
<p>
in the spin variables but symmetric in the space ones.
</p>
<p>
Therefore, in both cases, you are dealing with a "Bosonic" ground state.
</p> </p>
</div> </div>
</div> </div>
<div id="outline-container-orge14c674" class="outline-3"> <div id="outline-container-org420b954" class="outline-3">
<h3 id="orge14c674"><span class="section-number-3">4.3</span> Importance sampling</h3> <h3 id="org420b954"><span class="section-number-3">4.3</span> Importance sampling</h3>
<div class="outline-text-3" id="text-4-3"> <div class="outline-text-3" id="text-4-3">
<p> <p>
In a molecular system, the potential is far from being constant In a molecular system, the potential is far from being constant
@ -3272,24 +3286,63 @@ when \(\Psi_T\) gets closer to the exact wave function. It can be simulated by
changing the number of particles according to \(\exp\left[ -\delta t\, changing the number of particles according to \(\exp\left[ -\delta t\,
\left(E_L(\mathbf{r}) - E_T\right)\right]\) \left(E_L(\mathbf{r}) - E_T\right)\right]\)
where \(E_T\) is the constant we had introduced above, which is adjusted to where \(E_T\) is the constant we had introduced above, which is adjusted to
the running average energy and is introduced to keep the number of particles the running average energy to keep the number of particles
reasonably constant. reasonably constant.
</p> </p>
<p> <p>
This equation generates the <i>N</i>-electron density \(\Pi\), which is the This equation generates the <i>N</i>-electron density \(\Pi\), which is the
product of the ground state with the trial wave function. It product of the ground state with the trial wave function. You may then ask: how
introduces the constraint that \(\Pi(\mathbf{r},\tau)=0\) where can we compute the total energy of the system?
\(\Psi_T(\mathbf{r})=0\). In the few cases where the wave function has no nodes, </p>
such as in the hydrogen atom or the H<sub>2</sub> molecule, this
constraint is harmless and we can obtain the exact energy. But for <p>
systems where the wave function has nodes, this scheme introduces an To this aim, we use the mixed estimator of the energy:
error known as the <i>fixed node error</i>. </p>
\begin{eqnarray*}
E(\tau) &=& \frac{\langle \psi(tau) | \hat{H} | \Psi_T \rangle}{\frac{\langle \psi(tau) | \Psi_T \rangle}\\
&=& \frac{\int \psi(\mathbf{r},\tau) \hat{H} \Psi_T(\mathbf{r}) d\mathbf{r}}
{\int \psi(\mathbf{r},\tau) \Psi_T(\mathbf{r}) d\mathbf{r}} \\
&=& \int \psi(\mathbf{r},\tau) \Psi_T(\mathbf{r}) E_L(\mathbf{r}) d\mathbf{r}}
{\int \psi(\mathbf{r},\tau) \Psi_T(\mathbf{r}) d\mathbf{r}}
\end{eqnarray*}
<p>
Since, for large \(\tau\), we have that
</p>
<p>
\[
\Pi(\mathbf{r},\tau) =\psi(\mathbf{r},\tau) \Psi_T(\mathbf{r}) \rightarrow \Phi_0(\mathbf{r}) \Psi_T(\mathbf{r})\,,
\]
</p>
<p>
and, using that \(\hat{H}\) is Hermitian and that \(\Phi_0\) is an eigenstate of the Hamiltonian, we obtain
</p>
<p>
\[
E(\tau) = \frac{\langle \psi_\tau | \hat{H} | \Psi_T \rangle}
{\langle \psi_\tau | \Psi_T \rangle}
= \frac{\langle \Psi_T | \hat{H} | \psi_\tau \rangle}
{\langle \Psi_T | \psi_\tau \rangle}
\rightarrow E_0 \frac{\langle \Psi_T | \psi_\tau \rangle}
{\langle \Psi_T | \psi_\tau \rangle}
= E_0
\]
</p>
<p>
Therefore, we can compute the energy within DMC by generating the
density \(\Pi\) with random walks, and simply averaging the local
energies computed with the trial wave function.
</p> </p>
</div> </div>
<div id="outline-container-org872eba8" class="outline-4"> <div id="outline-container-org24db661" class="outline-4">
<h4 id="org872eba8"><span class="section-number-4">4.3.1</span> Appendix : Details of the Derivation</h4> <h4 id="org24db661"><span class="section-number-4">4.3.1</span> Appendix : Details of the Derivation</h4>
<div class="outline-text-4" id="text-4-3-1"> <div class="outline-text-4" id="text-4-3-1">
<p> <p>
\[ \[
@ -3350,68 +3403,13 @@ Defining \(\Pi(\mathbf{r},t) = \psi(\mathbf{r},\tau)
</div> </div>
</div> </div>
<div id="outline-container-org5d1b87c" class="outline-3">
<div id="outline-container-org2d4e0bf" class="outline-3"> <h3 id="org5d1b87c"><span class="section-number-3">4.4</span> Pure Diffusion Monte Carlo (PDMC)</h3>
<h3 id="org2d4e0bf"><span class="section-number-3">4.4</span> Fixed-node DMC energy</h3>
<div class="outline-text-3" id="text-4-4"> <div class="outline-text-3" id="text-4-4">
<p> <p>
Now that we have a process to sample \(\Pi(\mathbf{r},\tau) =
\psi(\mathbf{r},\tau) \Psi_T(\mathbf{r})\), we can compute the exact
energy of the system, within the fixed-node constraint, as:
</p>
<p>
\[
E = \lim_{\tau \to \infty} \frac{\int \Pi(\mathbf{r},\tau) E_L(\mathbf{r}) d\mathbf{r}}
{\int \Pi(\mathbf{r},\tau) d\mathbf{r}} = \lim_{\tau \to
\infty} E(\tau).
\]
</p>
<p>
\[
E(\tau) = \frac{\int \psi(\mathbf{r},\tau) \Psi_T(\mathbf{r}) E_L(\mathbf{r}) d\mathbf{r}}
{\int \psi(\mathbf{r},\tau) \Psi_T(\mathbf{r}) d\mathbf{r}}
= \frac{\int \psi(\mathbf{r},\tau) \hat{H} \Psi_T(\mathbf{r}) d\mathbf{r}}
{\int \psi(\mathbf{r},\tau) \Psi_T(\mathbf{r}) d\mathbf{r}}
= \frac{\langle \psi_\tau | \hat{H} | \Psi_T \rangle}
{\langle \psi_\tau | \Psi_T \rangle}
\]
</p>
<p>
As \(\hat{H}\) is Hermitian,
</p>
<p>
\[
E(\tau) = \frac{\langle \psi_\tau | \hat{H} | \Psi_T \rangle}
{\langle \psi_\tau | \Psi_T \rangle}
= \frac{\langle \Psi_T | \hat{H} | \psi_\tau \rangle}
{\langle \Psi_T | \psi_\tau \rangle}
= E[\psi_\tau] \frac{\langle \Psi_T | \psi_\tau \rangle}
{\langle \Psi_T | \psi_\tau \rangle}
= E[\psi_\tau]
\]
</p>
<p>
So computing the energy within DMC consists in generating the
density \(\Pi\) with random walks, and simply averaging the local
energies computed with the trial wave function.
</p>
</div>
</div>
<div id="outline-container-org53f374e" class="outline-3">
<h3 id="org53f374e"><span class="section-number-3">4.5</span> Pure Diffusion Monte Carlo (PDMC)</h3>
<div class="outline-text-3" id="text-4-5">
<p>
Instead of having a variable number of particles to simulate the Instead of having a variable number of particles to simulate the
branching process, one can choose to sample \([\Psi_T(\mathbf{r})]^2\) instead of branching process, one can consider the term
\(\psi(\mathbf{r},\tau) \Psi_T(\mathbf{r})\), and consider the term \(\exp \left( -\delta t\,( E_L(\mathbf{r}) - E_T} \right)\) as a
\(\exp \left( -\delta t\,( E_L(\mathbf{r}) - E_{\text{ref}} \right)\) as a
cumulative product of weights: cumulative product of weights:
</p> </p>
@ -3457,14 +3455,14 @@ code, so this is what we will do in the next section.
</div> </div>
</div> </div>
<div id="outline-container-org9a97445" class="outline-3"> <div id="outline-container-org8fce010" class="outline-3">
<h3 id="org9a97445"><span class="section-number-3">4.6</span> Hydrogen atom</h3> <h3 id="org8fce010"><span class="section-number-3">4.5</span> Hydrogen atom</h3>
<div class="outline-text-3" id="text-4-6"> <div class="outline-text-3" id="text-4-5">
</div> </div>
<div id="outline-container-org3ed78fd" class="outline-4"> <div id="outline-container-org1ae20b2" class="outline-4">
<h4 id="org3ed78fd"><span class="section-number-4">4.6.1</span> Exercise</h4> <h4 id="org1ae20b2"><span class="section-number-4">4.5.1</span> Exercise</h4>
<div class="outline-text-4" id="text-4-6-1"> <div class="outline-text-4" id="text-4-5-1">
<div class="exercise"> <div class="exercise">
<p> <p>
Modify the Metropolis VMC program to introduce the PDMC weight. Modify the Metropolis VMC program to introduce the PDMC weight.
@ -3562,9 +3560,9 @@ energy of H for any value of \(a\).
</div> </div>
</div> </div>
<div id="outline-container-org2e9047d" class="outline-5"> <div id="outline-container-orgd9f1564" class="outline-5">
<h5 id="org2e9047d"><span class="section-number-5">4.6.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5> <h5 id="orgd9f1564"><span class="section-number-5">4.5.1.1</span> Solution&#xa0;&#xa0;&#xa0;<span class="tag"><span class="solution">solution</span></span></h5>
<div class="outline-text-5" id="text-4-6-1-1"> <div class="outline-text-5" id="text-4-5-1-1">
<p> <p>
<b>Python</b> <b>Python</b>
</p> </p>
@ -3779,9 +3777,9 @@ A = 0.98788066666666663 +/- 7.2889356133441110E-005
</div> </div>
<div id="outline-container-org5f489b3" class="outline-3"> <div id="outline-container-org711f9e1" class="outline-3">
<h3 id="org5f489b3"><span class="section-number-3">4.7</span> <span class="todo TODO">TODO</span> H<sub>2</sub></h3> <h3 id="org711f9e1"><span class="section-number-3">4.6</span> <span class="todo TODO">TODO</span> H<sub>2</sub></h3>
<div class="outline-text-3" id="text-4-7"> <div class="outline-text-3" id="text-4-6">
<p> <p>
We will now consider the H<sub>2</sub> molecule in a minimal basis composed of the We will now consider the H<sub>2</sub> molecule in a minimal basis composed of the
\(1s\) orbitals of the hydrogen atoms: \(1s\) orbitals of the hydrogen atoms:
@ -3801,8 +3799,8 @@ the nuclei.
</div> </div>
<div id="outline-container-org2330d12" class="outline-2"> <div id="outline-container-org4874bf9" class="outline-2">
<h2 id="org2330d12"><span class="section-number-2">5</span> <span class="todo TODO">TODO</span> <code>[0/3]</code> Last things to do</h2> <h2 id="org4874bf9"><span class="section-number-2">5</span> <span class="todo TODO">TODO</span> <code>[0/3]</code> Last things to do</h2>
<div class="outline-text-2" id="text-5"> <div class="outline-text-2" id="text-5">
<ul class="org-ul"> <ul class="org-ul">
<li class="off"><code>[&#xa0;]</code> Give some hints of how much time is required for each section</li> <li class="off"><code>[&#xa0;]</code> Give some hints of how much time is required for each section</li>
@ -3818,7 +3816,7 @@ the H\(_2\) molecule at $R$=1.4010 bohr. Answer: 0.17406 a.u.</li>
</div> </div>
<div id="postamble" class="status"> <div id="postamble" class="status">
<p class="author">Author: Anthony Scemama, Claudia Filippi</p> <p class="author">Author: Anthony Scemama, Claudia Filippi</p>
<p class="date">Created: 2021-01-31 Sun 19:07</p> <p class="date">Created: 2021-02-01 Mon 08:08</p>
<p class="validation"><a href="http://validator.w3.org/check?uri=referer">Validate</a></p> <p class="validation"><a href="http://validator.w3.org/check?uri=referer">Validate</a></p>
</div> </div>
</body> </body>