Anisotropic contribution in multicenter polarizabilities and first hyperpolarizabilities. Ab initio MP2 calculations of acetylene, ethylene, ethane and benzene

Multicenter polarizabilities and first hyperpolarizabilities of acetylene, ethylene, ethane and benzene are evaluated by using ab initio MP2 polarized one-electron potentials for developing a reliable and simple polarizable potential. Combination of classical isotropic induced dipoles at atom centers with anisotropic induced dipoles along bonds is recommended for describing a strong and inhomogeneous field, which often encounters in molecular dynamics simulations of solutions including ions and biological systems.