RMC_POT (Reverse Monte Carlo using POTentials), a computer code for   modeling the structure of disordered systems containing molecules of   arbitrary complexity, using flexible molecular constraints and non-bonding   potentials
  An approach has been devised and tested for preserving the molecular geometry and taking into account energetic considerations during Reverse Monte Carlo modeling. Instead of the commonly used fixed neighbour constraints, where molecules are held together by constraining distance ranges available for the specified atom pairs, here molecules are kept together via bond, angle and dihedral potential energies. The scaled total potential energy contributed to the measure of the goodness-of-fit, thus the atoms could be prevented from drifting apart. In some of the simulations (Lennard-Jones and Coulombic) non-bonding potentials were also applied. The algorithm was successfully tested for the X-ray structure factor based structure study of liquid dimethyl trisulfide, for which material now significantly more sensible results have been obtained than during previous attempts via any earlier version of Reverse Monte Carlo modeling. It is envisaged that structural modeling of a large class of materials, primarily liquids and amorphous solids containing molecules of up to about 100 atoms, will make use of the new code in the near future. 
Orsolya Gereben and Laszlo Pusztai
cond-mat.dis-nn physics.chem-ph