Simple avoidance of Pauli repulsion errors in the generalized hybrid orbital (GHO) method

We assess transformation matrices in the combined quantum mechanical and molecular mechanical method based on generalized hybrid orbitals (GHO). In addition to the previous ones, we examine a restrained transformation matrix based on the assumption that all coefficients of the p-hybridized orbitals are uniform and each hybridized orbital points toward a vertex of a tetrahedron. It is clearly shown that the new implementation improves the accuracy of the GHO method reducing the error concerning the Pauli repulsion about auxiliary orbitals.