Hi In the manual (page 81) it mentions that when using a Gromos96 ff the LJ cut-off should be set at 1.4nm or more, I have been using 1.0nm, should this cause many problems? Thanks Jo Joanne Hanna Department of Chemistry University of Warwick Coventry CV4 7AL (02476) 574623 J.F.Hanna at warwick.ac.uk