Theoretical study of methylene blue: a new method to determine partial atomic charges; investigation of the interaction with guanine

We propose a new method to derive atomic charges from ab initio molecular orbital calculations. These charges fit accurately the ab initio electrostatic potential and, simultaneously, they retain some chemical meaning; particularly, they are close to the Mulliken charges. The atomic charges were then used to study the methylene blue-guanine complex in vacuo by means of a molecular dynamics simulation. The sensitivity of the results of that simulation with respect to the charges was tested by comparing the results of that simulation with those obtained using a set of MOPAC charges. (C) 1998 Elsevier Science B.V. All rights reserved.