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Full-Text Articles in Physical Sciences and Mathematics

Analysis Of The Potential Energy Surface Of Ar–Nh3, G. Chalasinski, S. M. Cybulski, M. M. Szczesniak, Steve Scheiner Jan 1989

Analysis Of The Potential Energy Surface Of Ar–Nh3, G. Chalasinski, S. M. Cybulski, M. M. Szczesniak, Steve Scheiner

Steve Scheiner

The combination of supermolecular Møller–Plesset treatment with the perturbation theory of intermolecular forces is applied in the analysis of the potential energy surface of Ar–NH3. Anisotropy of the self‐consistent field (SCF) potential is determined by the first‐order exchange repulsion. Second‐order dispersion energy, the dominating attractive contribution, is anisotropic in the reciprocal sense to the first‐order exchange, i.e., minima in one nearly coincide with maxima in the other. The estimated second‐order correlation correction to the exchange effect is nearly as large as a half ΔESCF in the minimum and has a ‘‘smoothing’’ effect on the anisotropy of …


Nonadditive Effects In Hf And Hcl Trimers, G. Chalasinski, S. M. Cybulski, M. M. Szczesniak, Steve Scheiner Jan 1989

Nonadditive Effects In Hf And Hcl Trimers, G. Chalasinski, S. M. Cybulski, M. M. Szczesniak, Steve Scheiner

Steve Scheiner

Nonadditive effects are calculated for (HF)3 and (HCl)3 complexes and analyzed via the combination of perturbation theory of intermolecular forces with Møller–Plesset perturbation theory (MPPT). In both systems the nonadditivity is dominated by the self‐consistent field (SCF) deformation effect, i.e., mutual polarization of the monomer wavefunctions. Heitler–London exchange and correlation effects are of secondary importance. Three‐body terms exhibit much lesser basis set dependence than the two‐body effects and even quite moderate basis sets which are not accurate enough for treatment of two‐body forces can yield three‐body effects of quantitative quality. This is due in large measure to the …