Localized molecular orbitals multipole

Note that a distinction is made between electrostatic and polarization energies. Thus the electrostatic term, Ue e, here refers to an interaction between monomer charge distributions as if they were infinitely separated (i.e., t/°le). A perturbative method is used to obtain polarization as a separate entity. The electrostatic and polarization contributions are expressed in terms of multipole expansions of the classical coulomb and induction energies. Electrostatic interactions are computed using a distributed multipole expansion up to and including octupoles at atom centers and bond midpoints. The polarization term is calculated from analytic dipole polarizability tensors for each localized molecular orbital (LMO) in the valence shell centered at the LMO charge centroid. These terms are derived from quantum calculations on the... 

Experimental chemistry is focused, in most cases, on molecules of a larger size than those for which fair calculations with correlation are possible. However, after thorough analysis of the situation, it turns out that the cost of the calculations does not necessarily increase very fast with the size of a molecule. Employing localized molecular orbitals and using the multipole expansion (see Appendix X available at booksite.elsevier.com/978-0-444-59436-5) of the integrals involving the orbitals separated in space causes, fa- elongated molecules, the cost of the post-Hartree-Fock calculations to scale linearly with the size of a molecule. It can he expected that if the methods described in... 

Other postprocessing techniques allow the computation of the density of states/molecular orbital structure, local charges on atoms or fragments of the system, dipole and multipoles, magnetic properties, and the electrostatic potential. Energy minimization can also be performed in the presence of perturbations, such as external fields or imposed electrode... 

Etchebest, C., R. Lavery, and A. Pullman. 1982. The Calculations of Molecular Electrostatic Potential from a Multipole Expansion Based on Localized Orbitals and Developed at Their Centroids Accuracy and Applicability for Macromolecular Computations. Theor. Chim. Acta 62, 17. 

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