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Practical formulation of accurate many-body potentials through the perturbative extension of diatomics-in-ionic-systems: Applied to HF clusters
 

Summary: Practical formulation of accurate many-body potentials through the
perturbative extension of diatomics-in-ionic-systems: Applied to HF clusters
M. Ovchinnikov and V. A. Apkariana)
Department of Chemistry, University of California, Irvine, California 92697-2025
Received 21 December 1998; accepted 18 February 1999
A perturbative extension of the diatomics-in-ionic-systems DIIS is formulated as a practical
method for describing global many-body potential energy surfaces with accuracy and economy. The
method is applied to HF clusters, generalizing the prior accurate DIIS treatment of the dimer
Grigorenko, Nemukhin, and Apkarian, J. Chem. Phys. 108, 4413 1998 to arbitrary numbers of
HF molecules. The calculated geometries, energetics, and harmonic frequencies of (HF)n , n
26 clusters agree in detail with the available data on this well-studied system. The formulation
is based on treating intermolecular interactions within perturbation theory. It is shown that
second-order perturbation, which includes bimolecular excitations, is necessary and sufficient in
describing the many-body potential energy surfaces with spectroscopic accuracy. The approach
allows the analysis of H-bonding and its nonadditive induction and dispersion forces in terms of
mixings and exchange between ground- and excited states of dimers including intra- and
intermolecular charge-transfer states as well as molecular triplet states. The speed of evaluation of
the potential scales is the cube of the number of molecules, providing a practical method for
dynamical simulations of extended hydrogen-bonded networks. 1999 American Institute of
Physics. S0021-9606 99 30119-7

  

Source: Apkarian, V. Ara - Department of Chemistry, University of California, Irvine

 

Collections: Chemistry