New concepts in bonded functions theory. I. alternative way of matrix elements evaluation

A new method of evaluation of energy matrix elements has been derived for bonded functions of Boys and a spinless Hamiltonian. In configuration‐driven CI algorithm the new approach is two to four times faster than the original Reeves' one, the relative speed depending on the case. In integral‐driven CI the new approach is about 10 to 12 times faster than the equivalent approach based on the Reeves' scheme.