Fast force field expressions for computer simulations

It is the aim of this work to develop analytical force field expressions that can be rapidly evaluated by computers. The new expressions approximate the energy hypersurfaces as described by the usual force fields. The energies and the derivatives of the energy expressions, i. e. the forces acting on the atoms, in most cases can be very quickly calculated as functions of one squared distance of two atoms per interaction, avoiding slow operations like cosine, square root etc. Formulae and algorithms are given to calculate the parameters needed from those of the AMBER force field.