Topology of the Electron Density and of Its Laplacian from Periodic LCAO Calculations on <i>f</i>-Electron Materials: The Case of Cesium Uranyl Chloride

• Main Authors: Alessandro Cossard, Silvia Casassa, Carlo Gatti, Jacques K. Desmarais, Alessandro Erba
• Format: Article
• Language: English
• Published: MDPI AG 2021-07-01
• Series: Molecules
• Subjects: chemical bonding; actinides; <span style="font-variant: small-caps">Topond</span> program
• Online Access: https://www.mdpi.com/1420-3049/26/14/4227

The chemistry of <i>f</i>-electrons in lanthanide and actinide materials is yet to be fully rationalized. Quantum-mechanical simulations can provide useful complementary insight to that obtained from experiments. The quantum theory of atoms in molecules and crystals (QTAIMAC), through thorough topological analysis of the electron density (often complemented by that of its Laplacian) constitutes a general and robust theoretical framework to analyze chemical bonding features from a computed wave function. Here, we present the extension of the <span style="font-variant: small-caps;">Topond</span> module (previously limited to work in terms of <i>s</i>-, <i>p</i>- and <i>d</i>-type basis functions only) of the <span style="font-variant: small-caps;">Crystal</span> program to <i>f</i>- and <i>g</i>-type basis functions within the linear combination of atomic orbitals (LCAO) approach. This allows for an effective QTAIMAC analysis of chemical bonding of lanthanide and actinide materials. The new implemented algorithms are applied to the analysis of the spatial distribution of the electron density and its Laplacian of the cesium uranyl chloride, Cs<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula>UO<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula>Cl<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>4</mn></msub></semantics></math></inline-formula>, crystal. Discrepancies between the present theoretical description of chemical bonding and that obtained from a previously reconstructed electron density by experimental X-ray diffraction are illustrated and discussed.