A SMOOTH PARTICLE MESH EWALD METHOD

The previously developed particle mesh Ewald method is reformulated in terms of efficient B-spline interpolation of the structure factors. T his reformulation allows a natural extension of the method to potentia ls of the form 1/r(p) with p greater than or equal to 1. Furthermore, efficient calculation of the virial tensor follows. Use of B-splines i n place of Lagrange interpolation leads to analytic gradients as well as a significant improvement in the accuracy. We demonstrate that arbi trary accuracy can be achieved, independent of system size N, at a cos t that scales as N log(N). For biomolecular systems with many thousand s of atoms this method permits the use of Ewald summation at a computa tional cost comparable to that of a simple truncation method of 10 ang stroms or less.