Intermolecular interaction energies by topologically partitioned electric properties. 1. Electrostatic and induction energies in one-center and multicenter multipole expansions.
Certain difficulties with the usual one-center multipole expansion of long-range intermol. interaction energies can be circumvented by multicenter multipole expansions using several expansion sites in each mol., such as, e.g., the nuclear positions. Based on the topol. partitioning of the mol. vol. provided by Bader's 'atoms in mols.' theory, a method has been developed for calcg. the required at. multipole moments and polarizabilities. The performance of these topol. partitioned elec. properties is examd. for the calcn. of multipole expanded first-order electrostatic and second-order induction energies by comparing their convergence behavior with that of the corresponding one-center expansions. The homomol. dimers of the water, carbon monoxide, cyanogen, and urea mols. serve as examples. The results show that distributed elec. properties calcd. within the topol. partitioning scheme indeed solve the 'shape' convergence problem, which arises in the calcn. of interaction energies of large nonspherical mols. via multipole expansions.
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