COUNTERPOISE PROCEDURE AND EQUILIBRIUM GEOMETRY OF HE-H2O COMPLEX

According to four potential energy surfaces of MP4 and SCF with/withou t counterpoise (CP) procedure, the influence of electronic correlation effect and CP to remove the superposition errors on the equilibrium g eometry of He-H2O complex is discussed and accurate equilibrium geomet ry of He-H2O is obtained. It is shown that the applications of both el ectronic correlation and CP are necessary in the calculations of weak van der Waals complex, by means of effective basis set.