1
0
mirror of https://github.com/TREX-CoE/trexio.git synced 2024-11-05 05:34:04 +01:00
trexio/examples.html

1165 lines
54 KiB
HTML

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
<head>
<!-- 2024-03-13 Wed 13:26 -->
<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<title>Examples</title>
<meta name="generator" content="Org mode" />
<meta name="author" content="TREX-CoE" />
<style type="text/css">
<!--/*--><![CDATA[/*><!--*/
.title { text-align: center;
margin-bottom: .2em; }
.subtitle { text-align: center;
font-size: medium;
font-weight: bold;
margin-top:0; }
.todo { font-family: monospace; color: red; }
.done { font-family: monospace; color: green; }
.priority { font-family: monospace; color: orange; }
.tag { background-color: #eee; font-family: monospace;
padding: 2px; font-size: 80%; font-weight: normal; }
.timestamp { color: #bebebe; }
.timestamp-kwd { color: #5f9ea0; }
.org-right { margin-left: auto; margin-right: 0px; text-align: right; }
.org-left { margin-left: 0px; margin-right: auto; text-align: left; }
.org-center { margin-left: auto; margin-right: auto; text-align: center; }
.underline { text-decoration: underline; }
#postamble p, #preamble p { font-size: 90%; margin: .2em; }
p.verse { margin-left: 3%; }
pre {
border: 1px solid #ccc;
box-shadow: 3px 3px 3px #eee;
padding: 8pt;
font-family: monospace;
overflow: auto;
margin: 1.2em;
}
pre.src {
position: relative;
overflow: visible;
padding-top: 1.2em;
}
pre.src:before {
display: none;
position: absolute;
background-color: white;
top: -10px;
right: 10px;
padding: 3px;
border: 1px solid black;
}
pre.src:hover:before { display: inline;}
/* Languages per Org manual */
pre.src-asymptote:before { content: 'Asymptote'; }
pre.src-awk:before { content: 'Awk'; }
pre.src-C:before { content: 'C'; }
/* pre.src-C++ doesn't work in CSS */
pre.src-clojure:before { content: 'Clojure'; }
pre.src-css:before { content: 'CSS'; }
pre.src-D:before { content: 'D'; }
pre.src-ditaa:before { content: 'ditaa'; }
pre.src-dot:before { content: 'Graphviz'; }
pre.src-calc:before { content: 'Emacs Calc'; }
pre.src-emacs-lisp:before { content: 'Emacs Lisp'; }
pre.src-fortran:before { content: 'Fortran'; }
pre.src-gnuplot:before { content: 'gnuplot'; }
pre.src-haskell:before { content: 'Haskell'; }
pre.src-hledger:before { content: 'hledger'; }
pre.src-java:before { content: 'Java'; }
pre.src-js:before { content: 'Javascript'; }
pre.src-latex:before { content: 'LaTeX'; }
pre.src-ledger:before { content: 'Ledger'; }
pre.src-lisp:before { content: 'Lisp'; }
pre.src-lilypond:before { content: 'Lilypond'; }
pre.src-lua:before { content: 'Lua'; }
pre.src-matlab:before { content: 'MATLAB'; }
pre.src-mscgen:before { content: 'Mscgen'; }
pre.src-ocaml:before { content: 'Objective Caml'; }
pre.src-octave:before { content: 'Octave'; }
pre.src-org:before { content: 'Org mode'; }
pre.src-oz:before { content: 'OZ'; }
pre.src-plantuml:before { content: 'Plantuml'; }
pre.src-processing:before { content: 'Processing.js'; }
pre.src-python:before { content: 'Python'; }
pre.src-R:before { content: 'R'; }
pre.src-ruby:before { content: 'Ruby'; }
pre.src-sass:before { content: 'Sass'; }
pre.src-scheme:before { content: 'Scheme'; }
pre.src-screen:before { content: 'Gnu Screen'; }
pre.src-sed:before { content: 'Sed'; }
pre.src-sh:before { content: 'shell'; }
pre.src-sql:before { content: 'SQL'; }
pre.src-sqlite:before { content: 'SQLite'; }
/* additional languages in org.el's org-babel-load-languages alist */
pre.src-forth:before { content: 'Forth'; }
pre.src-io:before { content: 'IO'; }
pre.src-J:before { content: 'J'; }
pre.src-makefile:before { content: 'Makefile'; }
pre.src-maxima:before { content: 'Maxima'; }
pre.src-perl:before { content: 'Perl'; }
pre.src-picolisp:before { content: 'Pico Lisp'; }
pre.src-scala:before { content: 'Scala'; }
pre.src-shell:before { content: 'Shell Script'; }
pre.src-ebnf2ps:before { content: 'ebfn2ps'; }
/* additional language identifiers per "defun org-babel-execute"
in ob-*.el */
pre.src-cpp:before { content: 'C++'; }
pre.src-abc:before { content: 'ABC'; }
pre.src-coq:before { content: 'Coq'; }
pre.src-groovy:before { content: 'Groovy'; }
/* additional language identifiers from org-babel-shell-names in
ob-shell.el: ob-shell is the only babel language using a lambda to put
the execution function name together. */
pre.src-bash:before { content: 'bash'; }
pre.src-csh:before { content: 'csh'; }
pre.src-ash:before { content: 'ash'; }
pre.src-dash:before { content: 'dash'; }
pre.src-ksh:before { content: 'ksh'; }
pre.src-mksh:before { content: 'mksh'; }
pre.src-posh:before { content: 'posh'; }
/* Additional Emacs modes also supported by the LaTeX listings package */
pre.src-ada:before { content: 'Ada'; }
pre.src-asm:before { content: 'Assembler'; }
pre.src-caml:before { content: 'Caml'; }
pre.src-delphi:before { content: 'Delphi'; }
pre.src-html:before { content: 'HTML'; }
pre.src-idl:before { content: 'IDL'; }
pre.src-mercury:before { content: 'Mercury'; }
pre.src-metapost:before { content: 'MetaPost'; }
pre.src-modula-2:before { content: 'Modula-2'; }
pre.src-pascal:before { content: 'Pascal'; }
pre.src-ps:before { content: 'PostScript'; }
pre.src-prolog:before { content: 'Prolog'; }
pre.src-simula:before { content: 'Simula'; }
pre.src-tcl:before { content: 'tcl'; }
pre.src-tex:before { content: 'TeX'; }
pre.src-plain-tex:before { content: 'Plain TeX'; }
pre.src-verilog:before { content: 'Verilog'; }
pre.src-vhdl:before { content: 'VHDL'; }
pre.src-xml:before { content: 'XML'; }
pre.src-nxml:before { content: 'XML'; }
/* add a generic configuration mode; LaTeX export needs an additional
(add-to-list 'org-latex-listings-langs '(conf " ")) in .emacs */
pre.src-conf:before { content: 'Configuration File'; }
table { border-collapse:collapse; }
caption.t-above { caption-side: top; }
caption.t-bottom { caption-side: bottom; }
td, th { vertical-align:top; }
th.org-right { text-align: center; }
th.org-left { text-align: center; }
th.org-center { text-align: center; }
td.org-right { text-align: right; }
td.org-left { text-align: left; }
td.org-center { text-align: center; }
dt { font-weight: bold; }
.footpara { display: inline; }
.footdef { margin-bottom: 1em; }
.figure { padding: 1em; }
.figure p { text-align: center; }
.equation-container {
display: table;
text-align: center;
width: 100%;
}
.equation {
vertical-align: middle;
}
.equation-label {
display: table-cell;
text-align: right;
vertical-align: middle;
}
.inlinetask {
padding: 10px;
border: 2px solid gray;
margin: 10px;
background: #ffffcc;
}
#org-div-home-and-up
{ text-align: right; font-size: 70%; white-space: nowrap; }
textarea { overflow-x: auto; }
.linenr { font-size: smaller }
.code-highlighted { background-color: #ffff00; }
.org-info-js_info-navigation { border-style: none; }
#org-info-js_console-label
{ font-size: 10px; font-weight: bold; white-space: nowrap; }
.org-info-js_search-highlight
{ background-color: #ffff00; color: #000000; font-weight: bold; }
.org-svg { width: 90%; }
/*]]>*/-->
</style>
<link rel="stylesheet" title="Standard" href="trexio.css" type="text/css" />
<script type="text/javascript" src="org-info.js">
/**
*
* @source: org-info.js
*
* @licstart The following is the entire license notice for the
* JavaScript code in org-info.js.
*
* Copyright (C) 2012-2020 Free Software Foundation, Inc.
*
*
* The JavaScript code in this tag is free software: you can
* redistribute it and/or modify it under the terms of the GNU
* General Public License (GNU GPL) as published by the Free Software
* Foundation, either version 3 of the License, or (at your option)
* any later version. The code is distributed WITHOUT ANY WARRANTY;
* without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU GPL for more details.
*
* As additional permission under GNU GPL version 3 section 7, you
* may distribute non-source (e.g., minimized or compacted) forms of
* that code without the copy of the GNU GPL normally required by
* section 4, provided you include this license notice and a URL
* through which recipients can access the Corresponding Source.
*
* @licend The above is the entire license notice
* for the JavaScript code in org-info.js.
*
*/
</script>
<script type="text/javascript">
/*
@licstart The following is the entire license notice for the
JavaScript code in this tag.
Copyright (C) 2012-2020 Free Software Foundation, Inc.
The JavaScript code in this tag is free software: you can
redistribute it and/or modify it under the terms of the GNU
General Public License (GNU GPL) as published by the Free Software
Foundation, either version 3 of the License, or (at your option)
any later version. The code is distributed WITHOUT ANY WARRANTY;
without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU GPL for more details.
As additional permission under GNU GPL version 3 section 7, you
may distribute non-source (e.g., minimized or compacted) forms of
that code without the copy of the GNU GPL normally required by
section 4, provided you include this license notice and a URL
through which recipients can access the Corresponding Source.
@licend The above is the entire license notice
for the JavaScript code in this tag.
*/
<!--/*--><![CDATA[/*><!--*/
org_html_manager.set("TOC_DEPTH", "4");
org_html_manager.set("LINK_HOME", "index.html");
org_html_manager.set("LINK_UP", "");
org_html_manager.set("LOCAL_TOC", "1");
org_html_manager.set("VIEW_BUTTONS", "0");
org_html_manager.set("MOUSE_HINT", "underline");
org_html_manager.set("FIXED_TOC", "0");
org_html_manager.set("TOC", "0");
org_html_manager.set("VIEW", "info");
org_html_manager.setup(); // activate after the parameters are set
/*]]>*///-->
</script>
<script type="text/javascript">
/*
@licstart The following is the entire license notice for the
JavaScript code in this tag.
Copyright (C) 2012-2020 Free Software Foundation, Inc.
The JavaScript code in this tag is free software: you can
redistribute it and/or modify it under the terms of the GNU
General Public License (GNU GPL) as published by the Free Software
Foundation, either version 3 of the License, or (at your option)
any later version. The code is distributed WITHOUT ANY WARRANTY;
without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU GPL for more details.
As additional permission under GNU GPL version 3 section 7, you
may distribute non-source (e.g., minimized or compacted) forms of
that code without the copy of the GNU GPL normally required by
section 4, provided you include this license notice and a URL
through which recipients can access the Corresponding Source.
@licend The above is the entire license notice
for the JavaScript code in this tag.
*/
<!--/*--><![CDATA[/*><!--*/
function CodeHighlightOn(elem, id)
{
var target = document.getElementById(id);
if(null != target) {
elem.cacheClassElem = elem.className;
elem.cacheClassTarget = target.className;
target.className = "code-highlighted";
elem.className = "code-highlighted";
}
}
function CodeHighlightOff(elem, id)
{
var target = document.getElementById(id);
if(elem.cacheClassElem)
elem.className = elem.cacheClassElem;
if(elem.cacheClassTarget)
target.className = elem.cacheClassTarget;
}
/*]]>*///-->
</script>
<script type="text/x-mathjax-config">
MathJax.Hub.Config({
displayAlign: "center",
displayIndent: "0em",
"HTML-CSS": { scale: 100,
linebreaks: { automatic: "false" },
webFont: "TeX"
},
SVG: {scale: 100,
linebreaks: { automatic: "false" },
font: "TeX"},
NativeMML: {scale: 100},
TeX: { equationNumbers: {autoNumber: "AMS"},
MultLineWidth: "85%",
TagSide: "right",
TagIndent: ".8em"
}
});
</script>
<script type="text/javascript"
src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js?config=TeX-AMS_HTML"></script>
</head>
<body>
<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">Examples</h1>
<div id="table-of-contents">
<h2>Table of Contents</h2>
<div id="text-table-of-contents">
<ul>
<li><a href="#orge26d9d0">1. Writing nuclear coordinates</a>
<ul>
<li><a href="#org7700984">1.1. C</a></li>
<li><a href="#org9112f51">1.2. Python</a></li>
<li><a href="#orga41ec17">1.3. Fortran</a></li>
</ul>
</li>
<li><a href="#org2582a84">2. Accessing sparse quantities (integrals)</a>
<ul>
<li><a href="#org30c0248">2.1. Fortran</a>
<ul>
<li><a href="#orge0e1a01">2.1.1. Declare Temporary variables</a></li>
<li><a href="#org5140957">2.1.2. Obtain the name of the TREXIO file from the command line, and open it for reading</a></li>
<li><a href="#orgf37b5b9">2.1.3. Read the nuclear repulsion energy</a></li>
<li><a href="#org7cb5c49">2.1.4. Read the number of molecular orbitals</a></li>
<li><a href="#org98d9d6d">2.1.5. Allocate memory</a></li>
<li><a href="#orgf0ee13e">2.1.6. Read one-electron quantities</a></li>
<li><a href="#org9af9468">2.1.7. Read two-electron quantities</a>
<ul>
<li><a href="#org2e823bc">2.1.7.1. Electron repulsion integrals</a></li>
<li><a href="#org366cb7a">2.1.7.2. Reduced density matrix</a></li>
</ul>
</li>
<li><a href="#org006858c">2.1.8. Compute the energy</a></li>
<li><a href="#orgdb059f1">2.1.9. Terminate</a></li>
</ul>
</li>
<li><a href="#org788ae8f">2.2. Python</a>
<ul>
<li><a href="#org839c315">2.2.1. Obtain the name of the TREXIO file from the command line, and open it for reading</a></li>
<li><a href="#org617c079">2.2.2. Read the nuclear repulsion energy</a></li>
<li><a href="#org0bfcf25">2.2.3. Read the number of molecular orbitals</a></li>
<li><a href="#org3e8c412">2.2.4. Read one-electron quantities</a></li>
<li><a href="#org53dee91">2.2.5. Read two-electron quantities</a>
<ul>
<li><a href="#orgfacc0aa">2.2.5.1. Electron repulsion integrals</a></li>
<li><a href="#orgac750a9">2.2.5.2. Reduced density matrix</a></li>
</ul>
</li>
<li><a href="#orgf50ad96">2.2.6. Compute the energy</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#orge8a0de0">3. Reading determinants</a>
<ul>
<li><a href="#org2d425c8">3.1. Fortran</a></li>
</ul>
</li>
</ul>
</div>
</div>
<div id="outline-container-orge26d9d0" class="outline-2">
<h2 id="orge26d9d0"><span class="section-number-2">1</span> Writing nuclear coordinates</h2>
<div class="outline-text-2" id="text-1">
<p>
Here is a demonstration of how to use TREXIO to write the nuclear
coordinates of a water molecule to a file. It shows the basic steps
involved in opening a file, writing the data, and closing the file,
as well as the necessary TREXIO functions to perform these actions.
</p>
</div>
<div id="outline-container-org7700984" class="outline-3">
<h3 id="org7700984"><span class="section-number-3">1.1</span> C</h3>
<div class="outline-text-3" id="text-1-1">
<div class="org-src-container">
<pre class="src src-c"><span style="color: #483d8b;">#include</span> <span style="color: #8b2252;">&lt;stdio.h&gt;</span>
<span style="color: #483d8b;">#include</span> <span style="color: #8b2252;">&lt;trexio.h&gt;</span>
<span style="color: #228b22;">int</span> <span style="color: #0000ff;">main</span>() {
<span style="color: #228b22;">int</span> <span style="color: #a0522d;">num</span> = 3; // <span style="color: #b22222;">Number of atoms</span>
<span style="color: #228b22;">double</span> <span style="color: #a0522d;">coord</span>[][3] = {
// <span style="color: #b22222;">xyz coordinates in atomic units</span>
0. , 0. , -0.24962655,
0. , 2.70519714, 1.85136466,
0. , -2.70519714, 1.85136466 };
<span style="color: #228b22;">trexio_exit_code</span> <span style="color: #a0522d;">rc</span>;
// <span style="color: #b22222;">Open the TREXIO file</span>
<span style="color: #228b22;">trexio_t</span>* <span style="color: #a0522d;">f</span> = trexio_open(<span style="color: #8b2252;">"water.trexio"</span>, <span style="color: #8b2252;">'w'</span>, TREXIO_HDF5, &amp;rc);
<span style="color: #a020f0;">if</span> (rc != TREXIO_SUCCESS) {
fprintf(stderr, <span style="color: #8b2252;">"Error: %s\n"</span>, trexio_string_of_error(rc));
<span style="color: #a020f0;">return</span> -1;
}
// <span style="color: #b22222;">Write the number of nuclei</span>
rc = trexio_write_nucleus_num (f, num);
<span style="color: #a020f0;">if</span> (rc != TREXIO_SUCCESS) {
fprintf(stderr, <span style="color: #8b2252;">"Error: %s\n"</span>, trexio_string_of_error(rc));
<span style="color: #a020f0;">return</span> -1;
}
// <span style="color: #b22222;">Write the nuclear coordinates</span>
rc = trexio_write_nucleus_coord (f, &amp;coord[0][0]);
<span style="color: #a020f0;">if</span> (rc != TREXIO_SUCCESS) {
fprintf(stderr, <span style="color: #8b2252;">"Error: %s\n"</span>, trexio_string_of_error(rc));
<span style="color: #a020f0;">return</span> -1;
}
// <span style="color: #b22222;">Close the TREXIO file</span>
rc = trexio_close(f);
<span style="color: #a020f0;">if</span> (rc != TREXIO_SUCCESS) {
fprintf(stderr, <span style="color: #8b2252;">"Error: %s\n"</span>, trexio_string_of_error(rc));
<span style="color: #a020f0;">return</span> -1;
}
<span style="color: #a020f0;">return</span> 0;
}
</pre>
</div>
</div>
</div>
<div id="outline-container-org9112f51" class="outline-3">
<h3 id="org9112f51"><span class="section-number-3">1.2</span> Python</h3>
<div class="outline-text-3" id="text-1-2">
<p>
This code uses the TREXIO Python binding to create a new TREXIO file named
<code>water.trexio</code>, and write the nuclear coordinates of a water molecule.
</p>
<p>
The <code>coord</code> variable is a list of three lists, each containing the x, y,
and z coordinates of the water molecule's nuclei.
</p>
<p>
The <code>with</code> statement is used to ensure the file is properly closed after
the write is complete.
</p>
<p>
The <code>trexio.write_nucleus_num</code> function is used to write the number of
nuclei in the system.
</p>
<p>
The <code>trexio.write_nucleus_coord</code> function is used to write the nuclear
coordinates of the system.
</p>
<div class="org-src-container">
<pre class="src src-python"><span style="color: #a020f0;">import</span> trexio
<span style="color: #a0522d;">coord</span> = [ # <span style="color: #b22222;">xyz coordinates in atomic units</span>
[0. , 0., -0.24962655],
[0. , 2.70519714, 1.85136466],
[0. , -2.70519714, 1.85136466]
]
# <span style="color: #b22222;">The Python API calls can raise `trexio.Error`</span>
# <span style="color: #b22222;">exceptions to be handled via try/except clauses</span>
# <span style="color: #b22222;">in the user application</span>
<span style="color: #a020f0;">with</span> trexio.File(<span style="color: #8b2252;">"water.trexio"</span>, <span style="color: #8b2252;">'w'</span>,
back_end=trexio.TREXIO_HDF5) <span style="color: #a020f0;">as</span> f:
trexio.write_nucleus_num(f, <span style="color: #483d8b;">len</span>(coord))
trexio.write_nucleus_coord(f, coord)
</pre>
</div>
</div>
</div>
<div id="outline-container-orga41ec17" class="outline-3">
<h3 id="orga41ec17"><span class="section-number-3">1.3</span> Fortran</h3>
<div class="outline-text-3" id="text-1-3">
<div class="org-src-container">
<pre class="src src-f90"><span style="color: #a020f0;">program</span> <span style="color: #0000ff;">trexio_water</span>
<span style="color: #a020f0;">use</span> <span style="color: #0000ff;">trexio</span>
<span style="color: #228b22;">integer</span>, <span style="color: #a020f0;">parameter</span> ::<span style="color: #a0522d;"> num=3 </span>! <span style="color: #b22222;">Number of nuclei</span>
<span style="color: #228b22;">double precision</span> ::<span style="color: #a0522d;"> coord(3,3) </span>! <span style="color: #b22222;">Array of atom coordinates</span>
<span style="color: #228b22;">integer</span>(trexio_t) ::<span style="color: #a0522d;"> f </span>! <span style="color: #b22222;">The TREXIO file handle</span>
<span style="color: #228b22;">integer</span>(trexio_exit_code) ::<span style="color: #a0522d;"> rc </span>! <span style="color: #b22222;">TREXIO return code</span>
<span style="color: #228b22;">character</span>*(128) ::<span style="color: #a0522d;"> err_msg </span>! <span style="color: #b22222;">String holding the error message</span>
coord(:,:) = <span style="color: #a020f0;">reshape</span>( (/ 0.d0 , 0.d0 , -0.24962655d0, <span style="color: #a020f0;">&amp;</span>
0.d0 , 2.70519714d0, 1.85136466d0, <span style="color: #a020f0;">&amp;</span>
0.d0 , -2.70519714d0, 1.85136466d0 /), <span style="color: #a020f0;">&amp;</span>
<span style="color: #a020f0;">shape</span>(coord) )
! <span style="color: #b22222;">Open the TREXIO file</span>
f = trexio_open (<span style="color: #8b2252;">'water.trexio'</span>, <span style="color: #8b2252;">'w'</span>, TREXIO_HDF5, rc)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">trexio_string_of_error</span>(rc, err_msg)
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'Error: '</span>//<span style="color: #a020f0;">trim</span>(err_msg)
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">exit</span>(-1)
<span style="color: #a020f0;">end if</span>
! <span style="color: #b22222;">Write the number of nuclei</span>
rc = trexio_write_nucleus_num (f, num)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">trexio_string_of_error</span>(rc, err_msg)
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'Error: '</span>//<span style="color: #a020f0;">trim</span>(err_msg)
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">exit</span>(-1)
<span style="color: #a020f0;">end if</span>
! <span style="color: #b22222;">Write the nuclear coordinates</span>
rc = trexio_write_nucleus_coord (f, coord)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">trexio_string_of_error</span>(rc, err_msg)
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'Error: '</span>//<span style="color: #a020f0;">trim</span>(err_msg)
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">exit</span>(-1)
<span style="color: #a020f0;">end if</span>
! <span style="color: #b22222;">Close the TREXIO file</span>
rc = trexio_close(f)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">trexio_string_of_error</span>(rc, err_msg)
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'Error: '</span>//<span style="color: #a020f0;">trim</span>(err_msg)
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">exit</span>(-1)
<span style="color: #a020f0;">end if</span>
<span style="color: #a020f0;">end program</span>
</pre>
</div>
</div>
</div>
</div>
<div id="outline-container-org2582a84" class="outline-2">
<h2 id="org2582a84"><span class="section-number-2">2</span> Accessing sparse quantities (integrals)</h2>
<div class="outline-text-2" id="text-2">
</div>
<div id="outline-container-org30c0248" class="outline-3">
<h3 id="org30c0248"><span class="section-number-3">2.1</span> Fortran</h3>
<div class="outline-text-3" id="text-2-1">
<div class="org-src-container">
<pre class="src src-f90"><span style="color: #a020f0;">program</span> <span style="color: #0000ff;">print_energy</span>
<span style="color: #a020f0;">use</span> <span style="color: #0000ff;">trexio</span>
<span style="color: #a020f0;">implicit</span> <span style="color: #228b22;">none</span>
<span style="color: #228b22;">character</span>*(128) ::<span style="color: #a0522d;"> filename </span>! <span style="color: #b22222;">Name of the input file</span>
<span style="color: #228b22;">integer</span> ::<span style="color: #a0522d;"> rc </span>! <span style="color: #b22222;">Return code for error checking</span>
<span style="color: #228b22;">integer</span>(8) ::<span style="color: #a0522d;"> f </span>! <span style="color: #b22222;">TREXIO file handle</span>
<span style="color: #228b22;">character</span>*(128) ::<span style="color: #a0522d;"> err_msg </span>! <span style="color: #b22222;">Error message</span>
</pre>
</div>
<p>
This program computes the energy as:
</p>
<p>
\[
E = E_{\text{NN}} + \sum_{ij} \gamma_{ij}\, \langle j | h | i \rangle\,
+\, \frac{1}{2} \sum_{ijkl} \Gamma_{ijkl}\, \langle k l | i j
\rangle\; \textrm{ with } \; 0 < i,j,k,l \le n
\]
One needs to read from the TREXIO file:
</p>
<dl class="org-dl">
<dt>\(n\)</dt><dd>The number of molecular orbitals</dd>
<dt>\(E_{\text{NN}}\)</dt><dd>The nuclear repulsion energy</dd>
<dt>\(\gamma_{ij}\)</dt><dd>The one-body reduced density matrix</dd>
<dt>\(\langle j |h| i \rangle\)</dt><dd>The one-electron Hamiltonian integrals</dd>
<dt>\(\Gamma_{ijkl}\)</dt><dd>The two-body reduced density matrix</dd>
<dt>\(\langle k l | i j \rangle\)</dt><dd>The electron repulsion integrals</dd>
</dl>
<div class="org-src-container">
<pre class="src src-f90"><span style="color: #228b22;">integer</span> ::<span style="color: #a0522d;"> n</span>
<span style="color: #228b22;">double precision</span> ::<span style="color: #a0522d;"> E, E_nn</span>
<span style="color: #228b22;">double precision</span>, <span style="color: #a020f0;">allocatable</span> ::<span style="color: #a0522d;"> D(:,:), h0(:,:)</span>
<span style="color: #228b22;">double precision</span>, <span style="color: #a020f0;">allocatable</span> ::<span style="color: #a0522d;"> G(:,:,:,:), W(:,:,:,:)</span>
</pre>
</div>
</div>
<div id="outline-container-orge0e1a01" class="outline-4">
<h4 id="orge0e1a01"><span class="section-number-4">2.1.1</span> Declare Temporary variables</h4>
<div class="outline-text-4" id="text-2-1-1">
<div class="org-src-container">
<pre class="src src-f90"><span style="color: #228b22;">integer</span> ::<span style="color: #a0522d;"> i, j, k, l, m</span>
<span style="color: #228b22;">integer</span>(8), <span style="color: #a020f0;">parameter</span> ::<span style="color: #a0522d;"> BUFSIZE = 100000_8</span>
<span style="color: #228b22;">integer</span>(8) ::<span style="color: #a0522d;"> offset, icount, size_max</span>
<span style="color: #228b22;">integer</span> ::<span style="color: #a0522d;"> buffer_index(4,BUFSIZE)</span>
<span style="color: #228b22;">double precision</span> ::<span style="color: #a0522d;"> buffer_values(BUFSIZE)</span>
<span style="color: #228b22;">double precision</span>, <span style="color: #a020f0;">external</span> ::<span style="color: #a0522d;"> ddot </span>! <span style="color: #b22222;">BLAS dot product</span>
</pre>
</div>
</div>
</div>
<div id="outline-container-org5140957" class="outline-4">
<h4 id="org5140957"><span class="section-number-4">2.1.2</span> Obtain the name of the TREXIO file from the command line, and open it for reading</h4>
<div class="outline-text-4" id="text-2-1-2">
<div class="org-src-container">
<pre class="src src-f90"><span style="color: #a020f0;">call</span> <span style="color: #0000ff;">getarg</span>(1, filename)
f = trexio_open (filename, <span style="color: #8b2252;">'r'</span>, TREXIO_AUTO, rc)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">trexio_string_of_error</span>(rc, err_msg)
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'Error opening TREXIO file: '</span>//<span style="color: #a020f0;">trim</span>(err_msg)
<span style="color: #a020f0;">stop</span>
<span style="color: #a020f0;">end if</span>
</pre>
</div>
</div>
</div>
<div id="outline-container-orgf37b5b9" class="outline-4">
<h4 id="orgf37b5b9"><span class="section-number-4">2.1.3</span> Read the nuclear repulsion energy</h4>
<div class="outline-text-4" id="text-2-1-3">
<div class="org-src-container">
<pre class="src src-f90">rc = trexio_read_nucleus_repulsion(f, E_nn)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">trexio_string_of_error</span>(rc, err_msg)
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'Error reading nuclear repulsion: '</span>//<span style="color: #a020f0;">trim</span>(err_msg)
<span style="color: #a020f0;">stop</span>
<span style="color: #a020f0;">end if</span>
</pre>
</div>
</div>
</div>
<div id="outline-container-org7cb5c49" class="outline-4">
<h4 id="org7cb5c49"><span class="section-number-4">2.1.4</span> Read the number of molecular orbitals</h4>
<div class="outline-text-4" id="text-2-1-4">
<div class="org-src-container">
<pre class="src src-f90">rc = trexio_read_mo_num(f, n)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">trexio_string_of_error</span>(rc, err_msg)
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'Error reading number of MOs: '</span>//<span style="color: #a020f0;">trim</span>(err_msg)
<span style="color: #a020f0;">stop</span>
<span style="color: #a020f0;">end if</span>
</pre>
</div>
</div>
</div>
<div id="outline-container-org98d9d6d" class="outline-4">
<h4 id="org98d9d6d"><span class="section-number-4">2.1.5</span> Allocate memory</h4>
<div class="outline-text-4" id="text-2-1-5">
<div class="org-src-container">
<pre class="src src-f90"><span style="color: #a020f0;">allocate</span>( D(n,n), h0(n,n) )
<span style="color: #a020f0;">allocate</span>( G(n,n,n,n), W(n,n,n,n) )
G(:,:,:,:) = 0.d0
W(:,:,:,:) = 0.d0
</pre>
</div>
</div>
</div>
<div id="outline-container-orgf0ee13e" class="outline-4">
<h4 id="orgf0ee13e"><span class="section-number-4">2.1.6</span> Read one-electron quantities</h4>
<div class="outline-text-4" id="text-2-1-6">
<div class="org-src-container">
<pre class="src src-f90">rc = trexio_has_mo_1e_int_core_hamiltonian(f)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">stop</span> <span style="color: #8b2252;">'No core hamiltonian in file'</span>
<span style="color: #a020f0;">end if</span>
rc = trexio_read_mo_1e_int_core_hamiltonian(f, h0)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">trexio_string_of_error</span>(rc, err_msg)
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'Error reading core Hamiltonian: '</span>//<span style="color: #a020f0;">trim</span>(err_msg)
<span style="color: #a020f0;">stop</span>
<span style="color: #a020f0;">end if</span>
rc = trexio_has_rdm_1e(f)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">stop</span> <span style="color: #8b2252;">'No 1e RDM in file'</span>
<span style="color: #a020f0;">end if</span>
rc = trexio_read_rdm_1e(f, D)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">trexio_string_of_error</span>(rc, err_msg)
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'Error reading one-body RDM: '</span>//<span style="color: #a020f0;">trim</span>(err_msg)
<span style="color: #a020f0;">stop</span>
<span style="color: #a020f0;">end if</span>
</pre>
</div>
</div>
</div>
<div id="outline-container-org9af9468" class="outline-4">
<h4 id="org9af9468"><span class="section-number-4">2.1.7</span> Read two-electron quantities</h4>
<div class="outline-text-4" id="text-2-1-7">
<p>
Reading is done with OpenMP. Each thread reads its own buffer, and
the buffers are then processed in parallel.
</p>
<p>
Reading the file requires a lock, so it is done in a critical
section. The <code>offset</code> variable is shared, and it is incremented in
the critical section. For each read, the function returns in
<code>icount</code> the number of read integrals, so this variable needs also
to be protected in the critical section when modified.
</p>
</div>
<div id="outline-container-org2e823bc" class="outline-5">
<h5 id="org2e823bc"><span class="section-number-5">2.1.7.1</span> Electron repulsion integrals</h5>
<div class="outline-text-5" id="text-2-1-7-1">
<div class="org-src-container">
<pre class="src src-f90">rc = trexio_has_mo_2e_int_eri(f)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">stop</span> <span style="color: #8b2252;">'No electron repulsion integrals in file'</span>
<span style="color: #a020f0;">end if</span>
rc = trexio_read_mo_2e_int_eri_size (f, size_max)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">trexio_string_of_error</span>(rc, err_msg)
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'Error reading number of ERIs: '</span>//<span style="color: #a020f0;">trim</span>(err_msg)
<span style="color: #a020f0;">stop</span>
<span style="color: #a020f0;">end if</span>
offset = 0_8
!<span style="color: #b22222;">$OMP PARALLEL DEFAULT(SHARED) PRIVATE(icount, i, j, k, l, &amp;</span>
!<span style="color: #b22222;">$OMP buffer_index, buffer_values, m)</span>
icount = BUFSIZE
<span style="color: #a020f0;">do while</span> (icount == BUFSIZE)
!<span style="color: #b22222;">$OMP CRITICAL</span>
<span style="color: #a020f0;">if</span> (offset &lt; size_max) <span style="color: #a020f0;">then</span>
rc = trexio_read_mo_2e_int_eri(f, offset, icount, buffer_index, buffer_values)
offset = offset + icount
<span style="color: #a020f0;">else</span>
icount = 0
<span style="color: #a020f0;">end if</span>
!<span style="color: #b22222;">$OMP END CRITICAL</span>
<span style="color: #a020f0;">do</span> m=1,icount
i = buffer_index(1,m)
j = buffer_index(2,m)
k = buffer_index(3,m)
l = buffer_index(4,m)
W(i,j,k,l) = buffer_values(m)
W(k,j,i,l) = buffer_values(m)
W(i,l,k,j) = buffer_values(m)
W(k,l,i,j) = buffer_values(m)
W(j,i,l,k) = buffer_values(m)
W(j,k,l,i) = buffer_values(m)
W(l,i,j,k) = buffer_values(m)
W(l,k,j,i) = buffer_values(m)
<span style="color: #a020f0;">end do</span>
<span style="color: #a020f0;">end do</span>
!<span style="color: #b22222;">$OMP END PARALLEL</span>
</pre>
</div>
</div>
</div>
<div id="outline-container-org366cb7a" class="outline-5">
<h5 id="org366cb7a"><span class="section-number-5">2.1.7.2</span> Reduced density matrix</h5>
<div class="outline-text-5" id="text-2-1-7-2">
<div class="org-src-container">
<pre class="src src-f90">rc = trexio_has_rdm_2e(f)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">stop</span> <span style="color: #8b2252;">'No two-body density matrix in file'</span>
<span style="color: #a020f0;">end if</span>
rc = trexio_read_rdm_2e_size (f, size_max)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">trexio_string_of_error</span>(rc, err_msg)
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'Error reading number of 2-RDM elements: '</span>//<span style="color: #a020f0;">trim</span>(err_msg)
<span style="color: #a020f0;">stop</span>
<span style="color: #a020f0;">end if</span>
offset = 0_8
!<span style="color: #b22222;">$OMP PARALLEL DEFAULT(SHARED) PRIVATE(icount, i, j, k, l, &amp;</span>
!<span style="color: #b22222;">$OMP buffer_index, buffer_values, m)</span>
icount = bufsize
<span style="color: #a020f0;">do while</span> (offset &lt; size_max)
!<span style="color: #b22222;">$OMP CRITICAL</span>
<span style="color: #a020f0;">if</span> (offset &lt; size_max) <span style="color: #a020f0;">then</span>
rc = trexio_read_rdm_2e(f, offset, icount, buffer_index, buffer_values)
offset = offset + icount
<span style="color: #a020f0;">else</span>
icount = 0
<span style="color: #a020f0;">end if</span>
!<span style="color: #b22222;">$OMP END CRITICAL</span>
<span style="color: #a020f0;">do</span> m=1,icount
i = buffer_index(1,m)
j = buffer_index(2,m)
k = buffer_index(3,m)
l = buffer_index(4,m)
G(i,j,k,l) = buffer_values(m)
<span style="color: #a020f0;">end do</span>
<span style="color: #a020f0;">end do</span>
!<span style="color: #b22222;">$OMP END PARALLEL</span>
</pre>
</div>
</div>
</div>
</div>
<div id="outline-container-org006858c" class="outline-4">
<h4 id="org006858c"><span class="section-number-4">2.1.8</span> Compute the energy</h4>
<div class="outline-text-4" id="text-2-1-8">
<p>
When the orbitals are real, we can use
</p>
\begin{eqnarray*}
E &=& E_{\text{NN}} + \sum_{ij} \gamma_{ij}\, \langle j | h | i \rangle\,
+\, \frac{1}{2} \sum_{ijkl} \Gamma_{ijkl}\, \langle k l | i j
\rangle \\
&=& E_{\text{NN}} + \sum_{ij} \gamma_{ij}\, \langle i | h | j \rangle\,
+\, \frac{1}{2} \sum_{ijkl} \Gamma_{ijkl}\, \langle i j | k l
\rangle \\
\end{eqnarray*}
<p>
As \((n,m)\) 2D arrays are stored in memory as \((n \times m)\) 1D
arrays, we could pass the matrices to the <code>ddot</code> BLAS function to
perform the summations in a single call for the 1-electron quantities.
Instead, we prefer to interleave the 1-electron (negative) and
2-electron (positive) summations to have a better cancellation of
numerical errors.
</p>
<p>
Here \(n^4\) can be larger than the largest possible 32-bit integer,
so it is not safe to pass \(n^4\) to the <code>ddot</code> BLAS
function. Hence, we perform \(n^2\) loops, using vectors of size \(n^2\).
</p>
<div class="org-src-container">
<pre class="src src-f90">
E = 0.d0
<span style="color: #a020f0;">do</span> l=1,n
E = E + ddot( n, D(1,l), 1, h0(1,l), 1 )
<span style="color: #a020f0;">do</span> k=1,n
E = E + 0.5d0 * ddot( n*n, G(1,1,k,l), 1, W(1,1,k,l), 1 )
<span style="color: #a020f0;">end do</span>
<span style="color: #a020f0;">end do</span>
E = E + E_nn
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'Energy: '</span>, E
</pre>
</div>
</div>
</div>
<div id="outline-container-orgdb059f1" class="outline-4">
<h4 id="orgdb059f1"><span class="section-number-4">2.1.9</span> Terminate</h4>
<div class="outline-text-4" id="text-2-1-9">
<div class="org-src-container">
<pre class="src src-f90"> <span style="color: #a020f0;">deallocate</span>( D, h0, G, W )
<span style="color: #a020f0;">end program</span>
</pre>
</div>
</div>
</div>
</div>
<div id="outline-container-org788ae8f" class="outline-3">
<h3 id="org788ae8f"><span class="section-number-3">2.2</span> Python</h3>
<div class="outline-text-3" id="text-2-2">
<div class="org-src-container">
<pre class="src src-python"><span style="color: #a020f0;">import</span> sys
<span style="color: #a020f0;">import</span> trexio
<span style="color: #a020f0;">import</span> numpy <span style="color: #a020f0;">as</span> np
<span style="color: #a0522d;">BUFSIZE</span> = 100000
</pre>
</div>
<p>
This program computes the energy as:
</p>
<p>
\[
E = E_{\text{NN}} + \sum_{ij} \gamma_{ij}\, \langle j | h | i \rangle\,
+\, \frac{1}{2} \sum_{ijkl} \Gamma_{ijkl}\, \langle k l | i j
\rangle\; \textrm{ with } \; 0 < i,j,k,l \le n
\]
One needs to read from the TREXIO file:
</p>
<dl class="org-dl">
<dt>\(n\)</dt><dd>The number of molecular orbitals</dd>
<dt>\(E_{\text{NN}}\)</dt><dd>The nuclear repulsion energy</dd>
<dt>\(\gamma_{ij}\)</dt><dd>The one-body reduced density matrix</dd>
<dt>\(\langle j |h| i \rangle\)</dt><dd>The one-electron Hamiltonian integrals</dd>
<dt>\(\Gamma_{ijkl}\)</dt><dd>The two-body reduced density matrix</dd>
<dt>\(\langle k l | i j \rangle\)</dt><dd>The electron repulsion integrals</dd>
</dl>
</div>
<div id="outline-container-org839c315" class="outline-4">
<h4 id="org839c315"><span class="section-number-4">2.2.1</span> Obtain the name of the TREXIO file from the command line, and open it for reading</h4>
<div class="outline-text-4" id="text-2-2-1">
<div class="org-src-container">
<pre class="src src-python"><span style="color: #a0522d;">filename</span> = sys.argv[1]
<span style="color: #a0522d;">f</span> = trexio.File(filename, <span style="color: #8b2252;">'r'</span>, trexio.TREXIO_AUTO)
</pre>
</div>
</div>
</div>
<div id="outline-container-org617c079" class="outline-4">
<h4 id="org617c079"><span class="section-number-4">2.2.2</span> Read the nuclear repulsion energy</h4>
<div class="outline-text-4" id="text-2-2-2">
<div class="org-src-container">
<pre class="src src-python"><span style="color: #a0522d;">E_nn</span> = trexio.read_nucleus_repulsion(f)
</pre>
</div>
</div>
</div>
<div id="outline-container-org0bfcf25" class="outline-4">
<h4 id="org0bfcf25"><span class="section-number-4">2.2.3</span> Read the number of molecular orbitals</h4>
<div class="outline-text-4" id="text-2-2-3">
<div class="org-src-container">
<pre class="src src-python"><span style="color: #a0522d;">n</span> = trexio.read_mo_num(f)
</pre>
</div>
</div>
</div>
<div id="outline-container-org3e8c412" class="outline-4">
<h4 id="org3e8c412"><span class="section-number-4">2.2.4</span> Read one-electron quantities</h4>
<div class="outline-text-4" id="text-2-2-4">
<div class="org-src-container">
<pre class="src src-python"><span style="color: #a020f0;">if</span> <span style="color: #a020f0;">not</span> trexio.has_mo_1e_int_core_hamiltonian(f):
<span style="color: #a020f0;">print</span>(<span style="color: #8b2252;">"No core hamiltonian in file"</span>)
sys.<span style="color: #008b8b;">exit</span>(-1)
<span style="color: #a0522d;">h0</span> = trexio.read_mo_1e_int_core_hamiltonian(f)
<span style="color: #a020f0;">if</span> <span style="color: #a020f0;">not</span> trexio.has_rdm_1e(f):
<span style="color: #a020f0;">print</span>(<span style="color: #8b2252;">"No 1e RDM in file"</span>)
sys.<span style="color: #008b8b;">exit</span>(-1)
<span style="color: #a0522d;">D</span> = trexio.read_rdm_1e(f)
</pre>
</div>
</div>
</div>
<div id="outline-container-org53dee91" class="outline-4">
<h4 id="org53dee91"><span class="section-number-4">2.2.5</span> Read two-electron quantities</h4>
<div class="outline-text-4" id="text-2-2-5">
</div>
<div id="outline-container-orgfacc0aa" class="outline-5">
<h5 id="orgfacc0aa"><span class="section-number-5">2.2.5.1</span> Electron repulsion integrals</h5>
<div class="outline-text-5" id="text-2-2-5-1">
<div class="org-src-container">
<pre class="src src-python"><span style="color: #a020f0;">if</span> <span style="color: #a020f0;">not</span> trexio.has_mo_2e_int_eri(f):
<span style="color: #a020f0;">print</span>(<span style="color: #8b2252;">"No electron repulsion integrals in file"</span>)
sys.<span style="color: #008b8b;">exit</span>(-1)
<span style="color: #a0522d;">size_max</span> = trexio.read_mo_2e_int_eri_size(f)
<span style="color: #a0522d;">offset</span> = 0
<span style="color: #a0522d;">icount</span> = BUFSIZE
<span style="color: #a0522d;">feof</span> = <span style="color: #008b8b;">False</span>
<span style="color: #a0522d;">W</span> = np.zeros( (n,n,n,n) )
<span style="color: #a020f0;">while</span> <span style="color: #a020f0;">not</span> feof:
<span style="color: #a0522d;">buffer_index</span>, <span style="color: #a0522d;">buffer_values</span>, <span style="color: #a0522d;">icount</span>, <span style="color: #a0522d;">feof</span> = trexio.read_mo_2e_int_eri(f, offset, icount)
<span style="color: #a020f0;">for</span> m <span style="color: #a020f0;">in</span> <span style="color: #483d8b;">range</span>(icount):
<span style="color: #a0522d;">i</span>, <span style="color: #a0522d;">j</span>, <span style="color: #a0522d;">k</span>, <span style="color: #a0522d;">l</span> = buffer_index[m]
<span style="color: #a0522d;">W</span>[i,j,k,l] = buffer_values[m]
<span style="color: #a0522d;">W</span>[k,j,i,l] = buffer_values[m]
<span style="color: #a0522d;">W</span>[i,l,k,j] = buffer_values[m]
<span style="color: #a0522d;">W</span>[k,l,i,j] = buffer_values[m]
<span style="color: #a0522d;">W</span>[j,i,l,k] = buffer_values[m]
<span style="color: #a0522d;">W</span>[j,k,l,i] = buffer_values[m]
<span style="color: #a0522d;">W</span>[l,i,j,k] = buffer_values[m]
<span style="color: #a0522d;">W</span>[l,k,j,i] = buffer_values[m]
</pre>
</div>
</div>
</div>
<div id="outline-container-orgac750a9" class="outline-5">
<h5 id="orgac750a9"><span class="section-number-5">2.2.5.2</span> Reduced density matrix</h5>
<div class="outline-text-5" id="text-2-2-5-2">
<div class="org-src-container">
<pre class="src src-python"><span style="color: #a020f0;">if</span> <span style="color: #a020f0;">not</span> trexio.has_rdm_2e(f):
<span style="color: #a020f0;">print</span>(<span style="color: #8b2252;">"No two-body density matrix in file"</span>)
<span style="color: #a0522d;">offset</span> = 0
<span style="color: #a0522d;">icount</span> = BUFSIZE
<span style="color: #a0522d;">feof</span> = <span style="color: #008b8b;">False</span>
<span style="color: #a0522d;">G</span> = np.zeros( (n,n,n,n) )
<span style="color: #a020f0;">while</span> <span style="color: #a020f0;">not</span> feof:
<span style="color: #a0522d;">buffer_index</span>, <span style="color: #a0522d;">buffer_values</span>, <span style="color: #a0522d;">icount</span>, <span style="color: #a0522d;">feof</span> = trexio.read_rdm_2e(f, offset, icount)
<span style="color: #a020f0;">for</span> m <span style="color: #a020f0;">in</span> <span style="color: #483d8b;">range</span>(icount):
<span style="color: #a0522d;">i</span>, <span style="color: #a0522d;">j</span>, <span style="color: #a0522d;">k</span>, <span style="color: #a0522d;">l</span> = buffer_index[m]
<span style="color: #a0522d;">G</span>[i,j,k,l] = buffer_values[m]
</pre>
</div>
</div>
</div>
</div>
<div id="outline-container-orgf50ad96" class="outline-4">
<h4 id="orgf50ad96"><span class="section-number-4">2.2.6</span> Compute the energy</h4>
<div class="outline-text-4" id="text-2-2-6">
<p>
When the orbitals are real, we can use
</p>
\begin{eqnarray*}
E &=& E_{\text{NN}} + \sum_{ij} \gamma_{ij}\, \langle j | h | i \rangle\,
+\, \frac{1}{2} \sum_{ijkl} \Gamma_{ijkl}\, \langle k l | i j
\rangle \\
&=& E_{\text{NN}} + \sum_{ij} \gamma_{ij}\, \langle i | h | j \rangle\,
+\, \frac{1}{2} \sum_{ijkl} \Gamma_{ijkl}\, \langle i j | k l
\rangle \\
\end{eqnarray*}
<div class="org-src-container">
<pre class="src src-python"><span style="color: #a0522d;">G</span> = np.reshape(G, (n*n, n*n) )
<span style="color: #a0522d;">W</span> = np.reshape(W, (n*n, n*n) )
<span style="color: #a0522d;">E</span> = E_nn
<span style="color: #a0522d;">E</span> += 0.5*<span style="color: #483d8b;">sum</span>( [ np.dot(G[:,l], W[:,l]) <span style="color: #a020f0;">for</span> l <span style="color: #a020f0;">in</span> <span style="color: #483d8b;">range</span>(n*n) ] )
<span style="color: #a0522d;">E</span> += <span style="color: #483d8b;">sum</span>( [ np.dot(D[:,l], h0[:,l]) <span style="color: #a020f0;">for</span> l <span style="color: #a020f0;">in</span> <span style="color: #483d8b;">range</span>(n) ] )
<span style="color: #a020f0;">print</span> (f<span style="color: #8b2252;">"Energy: {E}"</span>)
</pre>
</div>
</div>
</div>
</div>
</div>
<div id="outline-container-orge8a0de0" class="outline-2">
<h2 id="orge8a0de0"><span class="section-number-2">3</span> Reading determinants</h2>
<div class="outline-text-2" id="text-3">
</div>
<div id="outline-container-org2d425c8" class="outline-3">
<h3 id="org2d425c8"><span class="section-number-3">3.1</span> Fortran</h3>
<div class="outline-text-3" id="text-3-1">
<div class="org-src-container">
<pre class="src src-f90"><span style="color: #a020f0;">program</span> <span style="color: #0000ff;">test</span>
<span style="color: #a020f0;">use</span> <span style="color: #0000ff;">trexio</span>
<span style="color: #a020f0;">implicit</span> <span style="color: #228b22;">none</span>
<span style="color: #228b22;">character</span>*(128) ::<span style="color: #a0522d;"> filename </span>! <span style="color: #b22222;">Name of the input file</span>
<span style="color: #228b22;">integer</span>(trexio_exit_code) ::<span style="color: #a0522d;"> rc </span>! <span style="color: #b22222;">Return code for error checking</span>
<span style="color: #228b22;">integer</span>(trexio_t) ::<span style="color: #a0522d;"> trex_determinant_file </span>! <span style="color: #b22222;">TREXIO file handle</span>
<span style="color: #228b22;">character</span>*(128) ::<span style="color: #a0522d;"> err_msg </span>! <span style="color: #b22222;">Error message</span>
<span style="color: #228b22;">integer</span>*8, <span style="color: #a020f0;">allocatable</span> ::<span style="color: #a0522d;"> buffer(:,:,:)</span>
<span style="color: #228b22;">integer</span>(8) ::<span style="color: #a0522d;"> offset, icount, BUFSIZE</span>
<span style="color: #228b22;">integer</span> ::<span style="color: #a0522d;"> ndet, int64_num, m</span>
<span style="color: #228b22;">integer</span> ::<span style="color: #a0522d;"> occ_num_up, occ_num_dn</span>
<span style="color: #228b22;">integer</span>, <span style="color: #a020f0;">allocatable</span> ::<span style="color: #a0522d;"> orb_list_up(:), orb_list_dn(:)</span>
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">getarg</span>(1, filename)
trex_determinant_file = trexio_open(filename, <span style="color: #8b2252;">'r'</span>, TREXIO_AUTO, rc)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">trexio_string_of_error</span>(rc, err_msg)
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'Error opening TREXIO file: '</span>//<span style="color: #a020f0;">trim</span>(err_msg)
<span style="color: #a020f0;">stop</span>
<span style="color: #a020f0;">end if</span>
rc = trexio_read_determinant_num(trex_determinant_file, ndet)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">trexio_string_of_error</span>(rc, err_msg)
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'Error reading determinant_num: '</span>//<span style="color: #a020f0;">trim</span>(err_msg)
<span style="color: #a020f0;">stop</span>
<span style="color: #a020f0;">end if</span>
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'ndet'</span>, ndet
rc = trexio_get_int64_num(trex_determinant_file, int64_num)
<span style="color: #a020f0;">if</span> (rc /= TREXIO_SUCCESS) <span style="color: #a020f0;">then</span>
<span style="color: #a020f0;">call</span> <span style="color: #0000ff;">trexio_string_of_error</span>(rc, err_msg)
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'Error reading int64_num: '</span>//<span style="color: #a020f0;">trim</span>(err_msg)
<span style="color: #a020f0;">stop</span>
<span style="color: #a020f0;">end if</span>
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'int64_num'</span>, int64_num
BUFSIZE = 1000_8
<span style="color: #a020f0;">allocate</span>(buffer(int64_num, 2, BUFSIZE))
<span style="color: #a020f0;">allocate</span>(orb_list_up(int64_num*64), orb_list_dn(int64_num*64))
offset = 0_8
icount = BUFSIZE
<span style="color: #a020f0;">do while</span> (icount == BUFSIZE)
<span style="color: #a020f0;">if</span> (offset &lt; ndet) <span style="color: #a020f0;">then</span>
rc = trexio_read_determinant_list(trex_determinant_file, offset, icount, buffer)
offset = offset + icount
<span style="color: #a020f0;">else</span>
icount = 0
<span style="color: #a020f0;">end if</span>
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">'---'</span>
<span style="color: #a020f0;">do</span> m=1,icount
rc = trexio_to_orbital_list_up_dn(int64_num, buffer(1,1,m), <span style="color: #a020f0;">&amp;</span>
orb_list_up, orb_list_dn, occ_num_up, occ_num_dn)
<span style="color: #a020f0;">print</span> <span style="color: #8b2252;">'(100(I3,X))'</span>, (orb_list_up(1:occ_num_up)), (orb_list_dn(1:occ_num_dn))
<span style="color: #a020f0;">print</span> *, <span style="color: #8b2252;">''</span>
<span style="color: #a020f0;">end do</span>
<span style="color: #a020f0;">end do</span>
<span style="color: #a020f0;">deallocate</span>(buffer, orb_list_dn, orb_list_up)
end
</pre>
</div>
</div>
</div>
</div>
</div>
<div id="postamble" class="status">
<p class="author">Author: TREX-CoE</p>
<p class="date">Created: 2024-03-13 Wed 13:26</p>
<p class="validation"><a href="http://validator.w3.org/check?uri=referer">Validate</a></p>
</div>
</body>
</html>