Dear all, I have a graphene like surface (carbons on a hexagonal lattice with zero partial charges and some LJ parameters) with a drop of water placed on it. In principle, this is a hydrophobic surface and the drop should remain a droplet on it. However, surprisingly I am seeing that the drop is spreading within a 1 ns of the simulation. In the past I have done some similar simulations (with a different structure but basically zero partial charge surface and LJ) on which the drop remains a drop.
Does any body have any ideas of what I may be doing wrong? Pasted below is my mdp and top file. Briefly, I am doing NVT simulation, PME for electrostatics, TIP3P water model, the surface is frozen and intra-surface interactions are excluded, the cut-off distances are 1 nm, velocity rescale thermostat (I tried both with the entire system coupled to the same thermostat and with sheet and water being coupled to different thermostats). Any suggestions are welcome. My analysis suggests this comes from the long range electrostatics because we have tested the same thing in LAMMPS. When we turn off PPPM and use cut-off based Coulomb (~5 nm) in LAMMPS (yes now we have changed the software) we don't see the drop spreading. I have done so many simulations and to have this problem stumps me!! Thanks for being helpful always. Sapna #### MDP file Start #### dt = 0.002 ; time step nsteps = 1000000 ; number of steps nstcomm = 10 ; reset c.o.m. motion comm_mode = Linear nstxout = 2000 ; write coords nstvout = 2000 ; write velocities nstlog = 500 ; print to logfile nstenergy = 250 ; print energies xtc_grps = System ; group crds written in xtc nstxtcout = 250 ; freq write xtc files nstlist = 10 ; update pairlist ns_type = grid ; pairlist method coulombtype = PME ; algorithm for Coulomb rvdw = 1.00 ; cut-off for vdw rcoulomb = 1.00 ; cut-off for coulomb rlist = 1.00 ; cut-off for nearest neighbor Tcoupl = V-rescale ; temp coupling scheme ref_t = 300.0 ; temp of system tc-grps = System ; system to thermocouple tau_t = 0.5 ; strength of thermocoupling Pcoupl = No ; scheme for pressure coupling Pcoupltype = isotropic ; pressure geometry tau_p = 0.5 ; p-coupoling time compressibility = 4.5e-5 ; compressibility ref_p = 1.0 ; ref pressure DispCorr = EnerPres ; long range correction gen_vel = yes ; generate init. vel gen_temp = 280 ; init. temp. gen_seed = 372340 ; random seed constraints = hbonds ; constraining bonds with H constraint_algorithm = shake freeze_grps = GRO freezedim = Y Y Y energygrps = GRO energygrp_excl = GRO GRO #### MDP File End ##### -- View this message in context: http://gromacs.5086.x6.nabble.com/Water-spreading-on-graphene-tp5007497.html Sent from the GROMACS Users Forum mailing list archive at Nabble.com. -- gmx-users mailing list [email protected] http://lists.gromacs.org/mailman/listinfo/gmx-users * 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 [email protected]. * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
