Analysis of the transferability of atomic multipoles for aminoacids in modeling macromolecular charge distribution from fragments

摘要

Cumulative Atomic Multipole Moments were calculated for all natural amino acids and symmetric cyclic hexapeptides within Self-Consisted Field (SCF) and Density Functional Theory (DFT) approaches using a standard 6-31G(d,p) basis set. These data were used to analyze in detail the quality and the conformational and the intermolecular transferability of molecular charge distributions expressed in the atomic multipole form. Intermolecular interaction energies were reproduced reasonably by CAMM transformed from other conformations. Good transferability of CAMM based model was also achieved between similar molecular environments, which opens a route to modeling electrostatic effects in highly symmetric (e.g., crystalline) systems. Transferability deficiencies of various charge distribution models were analyzed and attributed to different levels of multipole expansion.