Extrapolation scheme during MD and geometry optimization

In the geometry optimization and molecular dynamics simulations, the restart files generated at the previous steps are automatically utilized at the next step to accelerate the convergence using an extrapolation scheme [44,45]. In the extrapolation scheme, the number of previous MD or geometry optimization steps can be controlled by a keyword:

   scf.ExtCharge.History      2        # default=2
From a series of benchmark calculations, 'scf.ExtCharge.History' of 2 works well and a larger number tends to be numerically unstable. So, users are recommended to use the default setting of 2.