Multistate density function theory and the construction of diabatic and adiabatic potential energy surfaces

Abstract

A multistate density function theory( MSDFT) based on valence bond theory was introduced. As an application,the MSDFT method was illustrated by the bond dissociation of H2 and the proton transfer between HNO3 and a water molecule. In the dissociation of H2,the MSDFT method yields a correct behavior as the two H atoms stretch to infinity,and gives a potential well in accord with second-order perturbation using complete active space( CASPT2). For the proton transfer process of HNO3,MSDFT can be used to yield both diabatic and adiabatic potential energy curves as a function of the proton transfer reaction coordinate. For the reaction barrier height,the inclusion of an ionic state in a three-state model can significantly improve the accuracy in barrier height in comparison with the high-level results.