Optimization of a spin-coupled wave function built with partially orthogonalized orbitals

We sketch the procedure that we are using to optimize a spin-coupled wave function built with partially orthogonalized orbitals. It is shown how it is possible to parametrize the orbitals in order to deal with independent variables while maintaining the partial orthogonalization and how to calculate first- and second-order derivatives with respect to these variables. A test calculation on CH₄ molecule is shown. © 1996 John Wiley & Sons, Inc.