A molecular dynamics simulation method based on combined quantum mechanical and classical potentials is proposed. This method computes the interactions between particles in a focus region, we call it Hot Spot , at quantum chemical level within an affordable computational effort. Application to solution chemistry was examined by simulating Li + solvation in liquid ammonia. The new method yields a coordination number of 4 in contrast to 6 obtained from pair-potential simulation. Dynamical properties were found in agreement with the structural change of the solvation shell. The semi-empirical MNDO method was also tested within this approach, but proved inappropriate for the treatment of electrolyte solutions.