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Wave functions derived from experiment. V. Investigation of electron densities, electrostatic potentials, and electron localization functions for noncentrosymmetric crystals
Author(s) -
Grimwood Daniel J.,
Bytheway Ian,
Jayatilaka Dylan
Publication year - 2003
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.10238
Subject(s) - chemistry , dipole , electron localization function , crystal (programming language) , electron density , electron , molecule , atomic physics , wave function , wannier function , hartree–fock method , vicinal , charge density , electron diffraction , molecular physics , computational chemistry , diffraction , physics , condensed matter physics , quantum mechanics , organic chemistry , computer science , programming language
The constrained Hartree–Fock method using experimental X‐ray diffraction data is extended and applied to the case of noncentrosymmetric molecular crystals. A new way to estimate the errors in derived properties as a derivative with respect to added Gaussian noise is also described. Three molecular crystals are examined: ammonia [NH 3 ], urea [CO(NH 2 ) 2 ], and alloxan [(CO) 4 (NH) 2 ]. The energetic and electrical properties of these molecules in the crystalline state are presented. In all cases, an enhancement of the dipole moment is observed upon application of the experimental constraint. It is found that the phases of the structure factors are robustly determined by the constrained Hartree–Fock model, even in the presence of simulated noise. Plots of the electron density, electrostatic potential, and the electron localization function for the molecules in the crystal are displayed. In general, relative to the Hartree–Fock model, there is a depletion of charge around hydrogen atoms and lone pair regions, and a build‐up of charge within the molecular framework near nuclei, directed along the bonds. The electron localization function plots reveal an increase in the pair density between vicinal hydrogen atoms. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 470–483, 2003