Solving a coupled perturbed equation by the residual cutting method

We applied the residual cutting (RC) method, which has excellent converging characteristics, as the numerical solution of elliptic partial differential equations, to the coupled perturbed (CP) equation. This method also shows robust and precise converging characteristics in solving the CP equation. For small molecules, it was as effective as the Pople method. As molecule size increases, the number of steps required to achieve convergence increases. For systems with large size of molecules, this method is shown to be more advantageous than the Pople method in convergence, required memory and the amount of calculation.