A NEW 5-SITE PAIR POTENTIAL FOR FORMIC-ACID IN LIQUID SIMULATIONS

We propose a new five-site pair potential for formic acid to be employ ed in liquid state simulations. The pair potential excellently fits to the MP2/6-31G(d) ab initio dimer potential surface, correctly capture s the characteristics of the most important regions of the potential, and locates all seven minima found in ab initio calculations. Both the rmodynamical quantities and total radial distribution functions for li quid formic acid were computed employing Monte Carlo simulation techni ques. We found excellent agreement between experiment and theory with respect to thermodynamics and structure. The results of the total radi al distribution functions exhibit significant improvement compared to the results of the OPLS parameter set.