Improved parameters for generating partial charges: Correlation with observed dipole moments
The Universal Force Field was initially combined with the Charge Equilibrium Scheme in the molecular mechanics program AMMP in order to generate partial charges for protein atoms. A new parameter set with improved generation of partial charges has been derived in order to analyse a wider range of atoms and compounds. The electrostatic parameters were modified to achieve better correlation with experimental dipole moments for a training set of 160 compounds, which included alkali metal halogenides, saturated and unsaturated hydrocarbons, alcohols, ethers, amines, thiols, sulphides, oxo compounds, aromatic and heteroaromatic molecules. The correlation coefficient for the calculated and experimental dipole moments was improved from 0.57 to 0.98. The new parameters were tested for another 149 compounds and the correlation coefficient increased from 0.48 to 0.85. The newly generated Modified Parameter Set for AMMP (MOPSA) improves the predictive power of the program, especially in the area of the macromolecular modelling and drug design, where the nonbonded energies play a crucial role.
partial charges dipole moments force field molecular mechanics uff