Deformed atoms in molecules: analytical representation of atomic densities for Gaussian type orbitals

The analytical representation of the molecular density previously developed for Slater functions (J. Fernández Rico, R. López, G. Ramírez, I. Ema, E. Ludeña, J. Comput. Chem. 25 (2004) 1355-1363) is extended to the densities obtained with Gaussian functions. Our tests show a quick convergence of the atomic expansion and a very high efficiency of the algorithm developed for the practical implementation of the procedure. These points are illustrated with the analysis of the density and the calculation of the electrostatic potential and field lines of the 4-amino pyridine.