Fast analytical evaluation of intermolecular electrostatic interaction energies using the pseudoatom representation of the electron density. III. Application to crystal structures via the Ewald and direct summation methods

The previously reported exact potential and multipole moment (EP/MM) method for fast and accurate evaluation of the intermolecular electrostatic interaction energies using the pseudoatom representation of the electron density [Volkov, Koritsanszky& Coppens (2004). Chem. Phys. Lett. 391, 170 – 175; Nguyen, Kisiel& Volkov (2018). Acta Cryst. A74, 524 – 536; Nguyen& Volkov (2019). Acta Cryst. A75, 448 – 464] is extended to the calculation of electrostatic interaction energies in molecular crystals using two newly developed implementations: (i) the Ewald summation (ES), which includes interactions up to the hexadecapolar level and the EP correction to account for short-range electron-density penetration effects, and (ii) the enhanced EP/MM-based direct summation (DS), which at sufficiently large intermolecular separations replaces the atomic multipole moment approximation to the electrostatic energy with that based on the molecular multipole moments. As in the previous study [Nguyen, Kisiel& Volkov (2018). Acta Cryst. A74, 524 – 536], the EP electron repulsion integral is evaluated analytically using the L ö wdin α -function approach. The resulting techniques, incorporated in the XDPROP module of the software package XD2016, have been tested on several small-molecule crystal systems (benzene, l-dopa, paracetamol, amino acids etc.) and the crystal structure of a 181-atom decapeptide molecule (Z = 4) using electron densities constructed via the University at Buffalo Asphe...

Source: Acta Crystallographica Section A - September 17, 2020 Category: Chemistry Authors: Nguyen, D. Macchi, P. Volkov, A. Tags: electrostatic interaction energy charge density pseudoatom model ö wdin α -function multipole expansion Ewald summation lattice sums research papers Source Type: research