VALTOPO: a program for the determination of atomic and molecular properties from experimental electron densities

VALTOPO is a program for the multipole refinement of accurate X-ray diffraction data and for the determination of electrostatic properties. It is a new version of VALRAY, including the quantum theory of atoms in molecules analysis as implemented in the TOPOND98 program. Two test structures, L-alanine and the complex of (E)-1,2-bis(4-pyridyl)ethylene with 1,4-diiodotetrafluorobenzene, have been analysed in order to illustrate some of the potentialities of the program.