The use of nonlinear estimation techniques in simple molecular orbital calculations

Nonlinear estimation techniques have been applied to simple π-electron molecular orbital calculations which seek to have self-consistent Coulomb integrals and charge densities. Having analytic expressions for the various derivatives involved allows one to use the Newton-Raphson-Gauss estimation procedure, rather than iteration by substitution, as is customarily done. The present procedure converges very rapidly to the self-consistent solution, in contrast with the slow convergence or even divergence of the previous method.