Conformational Dependence of Isotropic Polarizabilities

摘要

We perform a statistical and energetic analysis of atomic polarizabilities obtained with the LoProp approach for all atomsin the avidin tetramer for 70 snapshots from molecular dynamics simulations with seven different biotin analogues, and fromthe crystal structure of the photosynthetic reaction center (in total 560 698 individual polarizabilities). Dynamic effectsgive a variation of the polarizabilities of 0.09 A~3 on average. Atoms at different positions in the sequence show avariation of 0.14 A on average, caused by the conformational dependence of the polarizabilities. This variation gives errorsof 2 and 1 kJ/mol for relative conformational and ligand-binding induction energies. Averaged elementwise or atom-typepolarizabilities give larger errors, e.g., 9 and 7 kJ/mol, respectively, for the relative conformational energies. Therefore,we recommend that polarizabilities should be assigned atomwise (i.e., individual polarizabilities for each atom in allresidues), in the same way as for charges. We provide such a set of extensively averaged polarizabilities (xAvPol) for allatoms in avidin and the photosynthetic reaction center, applicable at the B3LYP/aug-cc-pVTZ level, which is converged withrespect to the basis-set limit.