Hi,
i meant to perform a free energy calculation to get the chemical potential of water, and made a number of input files based on the excellent tutorial by Justin Lemkul. (Without thinking) I also tried using a tabulated potential for electrostatics with: coulombtype = User but it seems to work - all the numbers in dhdl.xvg are finite and non-zero, and neither mdrun nor grompp give me a warning) but then it shouldn't work ... how is Gromacs supposed to calculate the dU/dlambda term ? or Is this calculated numerically? or did i overlook something here? below my mdp file thanks for any advice! michael mdp: integrator = sd nsteps = 100000 dt = 0.002 ; pbc = xyz nstcomm = 100 comm_grps = System ; nstxtcout = 0 nstenergy = 100 nst_log = 0 nstxout = 0 nstvout = 0 ; rlist = 1.35 ; coulombtype = User rcoulomb = 1.2 vdw-type = switch rvdw-switch = 1.0 rvdw = 1.2 ; tc_grps = system tau_t = 1.0 ref_t = 300 ; Pcoupl = Berendsen tau_p = 0.5 compressibility = 4.5e-5 ref_p = 1.0 pcoupltype = isotropic ; constraints = hbonds lincs_iter = 8 ; free_energy = yes init_lambda = 0.50 delta_lambda = 0 foreign_lambda = 0.40 0.60 dhdl_derivatives = yes sc_alpha = 0.5 sc_power = 1 sc_sigma = 0.5 nstdhdl = 100 couple-moltype = w1 couple-lambda0 = vdw-q couple-lambda1 = none couple-intramol = no =============================== Why be happy when you could be normal? -- gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users * Only plain text messages are allowed! * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! * Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists