https://qtcovi.github.io/tag/electron-density/Electron DensityHugo Blox Builder (https://hugoblox.com)en-usMon, 01 Jan 2024 00:00:00 +0000https://qtcovi.github.io/media/icon_hu11734318148517933569.pnghttps://qtcovi.github.io/tag/electron-density/https://qtcovi.github.io/software/critic2/Mon, 01 Jan 2024 00:00:00 +0000https://qtcovi.github.io/software/critic2/<h2 id="about">About</h2> <p><strong>critic2</strong> is an open-source program for the topological analysis of scalar fields—most commonly the electron density—in both molecular and periodic (crystal) systems. It supports a wide range of quantum chemistry and plane-wave DFT codes as input sources.</p> <p>Key capabilities include:</p> <ul> <li><strong>Critical point search</strong> — bonds, rings, and cages from any scalar field.</li> <li><strong>QTAIM integration</strong> — atomic charges, volumes, and multipole moments.</li> <li><strong>Delocalization indices</strong> — from promolecular or DFT-level densities.</li> <li><strong>NCI visualisation</strong> — reduced density gradient isosurfaces for non-covalent interaction analysis.</li> <li><strong>Crystal structure analysis</strong> — symmetry, powder diffraction, intermolecular interaction energies.</li> </ul> <h2 id="links">Links</h2> <ul> <li><a href="https://github.com/aoterodelaroza/critic2" target="_blank" rel="noopener">GitHub repository</a></li> <li><a href="https://aoterodelaroza.github.io/critic2/" target="_blank" rel="noopener">Documentation</a></li> </ul> <h2 id="citation">Citation</h2> <blockquote> <p>A. Otero-de-la-Roza, E. R. Johnson, V. Luaña, <em>Comput. Phys. Commun.</em> <strong>185</strong>, 1007 (2014). A. Otero-de-la-Roza, M. A. Blanco, A. M. Pendás, V. Luaña, <em>Comput. Phys. Commun.</em> <strong>180</strong>, 157 (2009).</p> </blockquote>https://qtcovi.github.io/research/quantum-chemical-topology/Mon, 01 Jan 2024 00:00:00 +0000https://qtcovi.github.io/research/quantum-chemical-topology/<h2 id="overview">Overview</h2> <p>Quantum Chemical Topology (QCT) encompasses a family of methods that use the topology of scalar fields derived from the electron density—such as the gradient of ρ(r), the electron localisation function (ELF), or the non-covalent interaction (NCI) index—to partition molecular space into chemically meaningful regions (atoms, bonds, rings, cages).</p> <p>The cornerstone of QCT is Bader&rsquo;s <strong>Quantum Theory of Atoms in Molecules (QTAIM)</strong>, which defines atoms as basin-like regions bounded by zero-flux surfaces of the electron density gradient. Critical points of ρ(r) identify bond, ring, and cage features, while integrated atomic properties (charge, kinetic energy, volume) carry well-defined quantum mechanical meaning.</p> <h2 id="our-contributions">Our Contributions</h2> <ul> <li>Development of <strong>PROMOLDEN</strong>, a high-performance code for topological analysis of electron densities and pair densities.</li> <li>Systematic study of basin properties and their relationship to bonding descriptors.</li> <li>Extension of QCT frameworks to pair and reduced density matrices.</li> </ul> <h2 id="key-references">Key References</h2> <p>Selected publications from the group on quantum chemical topology are listed in the <a href="https://qtcovi.github.io/publication">Publications</a> section.</p>