ON THE CONVERGENCE OF THE SHAKE ALGORITHM

Several aspects of the convergence speed for the SHAKE iterative technique are reviewed. Two examples of molecular geometry which are known to have slow SHAKE convergence are used to show that simple changes to the procedure can result in a five-fold improvement in convergence speed. Fortran code, relevant to fully atomic models of alkane chains, is presented which is suitable for use in MD programs. Aspects of convergence criteria and constraint tolerance are also discussed.