Dear Sir, I am sufferering from a dmpc-bilayer-area shrinking problem. The fact is the experimental area at 300K is 59.6A2, where I am always getting 54A2 or 55A2 area. The dmpc_npat.pdb along with lipi.itp and dmpc.itp was taken from the Tieleman's site, and I tried to modify these with half-epsilon double pairlist method to combine OPLS-BERGER.
I am doing an initial minimisation (4500 steps with emtop 100) with flexible SPC and then turing on SETTLE and LINCS i am doing a pr-dynamics for 250ps and then MD run for 5ns. In the pr-dynamics, the area is around the original, but after starting MD, the area starts shrinking in 50ps only, and become continuous near 54A2. I know, 500ps is not sufficient for equilibration but the area shows no sign to again increase. The pr.mdp is: title = bilayer MD DMPC POSRES PURE cpp = /usr/bin/cpp define = -DDMPCPOSRES constraints = all-bonds constraint_algorithm= lincs lincs_order = 4 lincs_warnangle = 30 integrator = md dt = 0.002 ; ps ! nsteps = 125000 ; total 100 ps. nstcomm = 1 comm-mode = linear nstxout = 5000 nstvout = 5000 nstfout = 5000 nstenergy = 1000 nstlist = 5 ns_type = grid rlist = 0.9 rcoulomb = 0.9 vdwtype = Cut-off rvdw = 1.4 fourierspacing = 0.12 fourier_nx = 0 fourier_ny = 0 fourier_nz = 0 coulombtype = PME pme_order = 4 ewald_rtol = 1e-5 optimize_fft = yes ; Berendsen temperature coupling is on in two groups Tcoupl = berendsen tau_t = 0.1 0.1 tc-grps = DMPC sol ref_t = 300 300 ; Pressure coupling is not on Pcoupl = berendsen tau_p = 4.0 4.0 compressibility = 4.5e-5 4.5e-5 ref_p = 1.0 1.0 pcoupltype = semiisotropic ; Generate velocites is on at 300 K. gen_vel = yes gen_temp = 300.0 gen_seed = 173529 the md.mdp file is: title = bilayer MD DMPC PURE cpp = /usr/bin/cpp constraints = all-bonds constraint_algorithm= lincs lincs_order = 4 lincs_warnangle = 30 integrator = md dt = 0.002 ; ps ! nsteps = 2500000 ; total 100 ps. nstcomm = 1 comm-mode = linear nstxout = 5000 nstvout = 5000 nstfout = 5000 nstenergy = 1000 nstlist = 5 ns_type = grid rlist = 0.9 rcoulomb = 0.9 vdwtype = Cut-off rvdw = 1.4 fourierspacing = 0.12 fourier_nx = 0 fourier_ny = 0 fourier_nz = 0 coulombtype = PME pme_order = 4 ewald_rtol = 1e-5 optimize_fft = yes ; Berendsen temperature coupling is on in two groups Tcoupl = berendsen tau_t = 0.1 0.1 tc-grps = DMPC sol ref_t = 300 300 ; Pressure coupling is not on Pcoupl = berendsen tau_p = 4.0 4.0 compressibility = 4.5e-5 4.5e-5 ref_p = 1.0 1.0 pcoupltype = semiisotropic ; Generate velocites is on at 300 K. gen_vel = yes gen_temp = 300.0 gen_seed = 173529 the ffoplsaamd.itp is: #define _FF_OPLS #define _FF_OPLSAA ; This force field uses a format that requires Gromacs 3.1.4 or later. ; ; References for the OPLS-AA force field: ; ; W. L. Jorgensen, D. S. Maxwell, and J. Tirado-Rives, ; J. Am. Chem. Soc. 118, 11225-11236 (1996). ; W. L. Jorgensen and N. A. McDonald, Theochem 424, 145-155 (1998). ; W. L. Jorgensen and N. A. McDonald, J. Phys. Chem. B 102, 8049-8059 (1998). ; R. C. Rizzo and W. L. Jorgensen, J. Am. Chem. Soc. 121, 4827-4836 (1999). ; M. L. Price, D. Ostrovsky, and W. L. Jorgensen, J. Comp. Chem. (2001). ; E. K. Watkins and W. L. Jorgensen, J. Phys. Chem. A 105, 4118-4125 (2001).. ; G. A. Kaminski, R.A. Friesner, J.Tirado-Rives and W.L. Jorgensen, J. Phys.. Chem. B 105, 6474 (2001). ; [ defaults ] ; nbfunc comb-rule gen-pairs fudgeLJ fudgeQQ 1 3 yes 0.5 0.5 #include "ffoplsaanbmd.itp" #include "ffoplsaabon.itp" the ffoplsaanbmd.itp is: [ atomtypes ] ; full atom descriptions are available in ffoplsaa.atp ; name bond_type mass charge ptype sigma epsilon LO LO 1 15.9994 0.000 A 0.296 0.87721 ;carbonyl O, OPLS LOM LOM 1 15.9994 0.000 A 0.296 0.87721 ;carboxyl O, OPLS LNL LNL 1 14.0067 0.000 A 0.325 0.7107 ;Nitrogen, OPLS LC LC 1 12.0110 0.000 A 0.37499 0.43967 ;Carbonyl C, OPLS LH1 LH1 1 13.0190 0.000 A 0.38002 0.33451 ;CH1, OPLS LH2 LH2 1 14.0270 0.000 A 0.3905 0.49353 ;CH2, OPLS LP LP 1 30.9738 0.000 A 0.37400 0.83653 ;phosphor, OPLS LOS LOS 1 15.9994 0.000 A 0.29285 1.0158 ;ester oxygen, OPLS LP2 LP2 1 14.0270 0.000 A 0.29999 0.87809 ;RB CH2, Bergers LJ LP3 LP3 1 15.0350 0.000 A 0.396 0.568937 ;RB CH3, Bergers LJ LC3 LC3 1 15.0350 0.000 A 0.39601 0.67601 ;CH3, OPLS LC2 LC2 1 14.0270 0.000 A 0.3798 0.49419 ;CH2, OPLS .......................OPLS lines................................ [ pairtypes ] ; i j func sigma epsilon LO LO 1 0.29604 0.05482 LO LOM 1 0.29604 0.05482 LO opls_113 1 0.30632 0.04733 LO LNL 1 0.31018 0.04938 LO LC 1 0.33319 0.0388 LO LH1 1 0.33542 0.03383 LO LH2 1 0.34001 0.04111 LO LP 1 0.33275 0.05353 LO LOS 1 0.29799 0.0549 LO LP2 1 0.34237 0.03614 LO LP3 1 0.34239 0.04414 LO LC3 1 0.34238 0.04559 LO LC2 1 0.33539 0.04115 LOM LOM 1 0.29604 0.05482 LOM opls_113 1 0.30632 0.04733 LOM LNL 1 0.31018 0.04938 LOM LC 1 0.33319 0.0388 LOM LH1 1 0.33542 0.03383 LOM LH2 1 0.34001 0.04111 LOM LP 1 0.33275 0.05353 LOM LOS 1 0.29799 0.0549 LOM LP2 1 0.34237 0.03614 LOM LP3 1 0.34239 0.04414 LOM LC3 1 0.34238 0.04559 LOM LC2 1 0.33539 0.04115 opls_113 LNL 1 0.32095 0.04262 opls_113 LC 1 0.34478 0.03347 opls_113 LH1 1 0.34708 0.02921 opls_113 LH2 1 0.35181 0.0355 opls_113 LP 1 0.3443 0.04621 opls_113 LOS 1 0.30836 0.04737 opls_113 LP2 1 0.35427 0.0312 opls_113 LP3 1 0.35427 0.03812 opls_113 LC3 1 0.35428 0.03936 opls_113 LC2 1 0.34705 0.03551 LNL LNL 1 0.325 0.04446 LNL LC 1 0.34912 0.03492 LNL LH1 1 0.35145 0.03047 LNL LH2 1 0.35625 0.03703 LNL LP 1 0.34864 0.04822 LNL LOS 1 0.31224 0.04944 LNL LP2 1 0.35875 0.03254 LNL LP3 1 0.35877 0.03975 LNL LC3 1 0.35875 0.04106 LNL LC2 1 0.35139 0.03707 LC LC 1 0.37504 0.2743 LC LH1 1 0.37751 0.02395 LC LH2 1 0.3827 0.02908 LC LP 1 0.37452 0.03787 LC LOS 1 0.33542 0.03882 LC LP2 1 0.38535 0.25565 LC LP3 1 0.38539 0.03122 LC LC3 1 0.38537 0.03225 LC LC2 1 0.37751 0.02909 LH1 LH1 1 0.38004 0.02089 LH1 LH2 1 0.38525 0.02538 LH1 LP 1 0.37701 0.03305 LH1 LOS 1 0.33765 0.03388 LH1 LP2 1 0.38793 0.0223 LH1 LP3 1 0.38793 0.02724 LH1 LC3 1 0.38794 0.02814 LH1 LC2 1 0.38003 0.02539 LH2 LH2 1 0.39054 0.03082 LH2 LP 1 0.38218 0.04016 LH2 LOS 1 0.34227 0.04115 LH2 LP2 1 0.39324 0.0271 LH2 LP3 1 0.39328 0.03309 LH2 LC3 1 0.39324 0.03421 LH2 LC2 1 0.38523 0.03085 LP LP 1 0.37399 0.0523 LP LOS 1 0.33496 0.05359 LP LP2 1 0.38483 0.03529 LP LP3 1 0.38489 0.04306 LP LC3 1 0.38487 0.04451 LP LC2 1 0.37699 0.04017 LOS LOS 1 0.29998 0.05495 LOS LP2 1 0.34464 0.36185 LOS LP3 1 0.34468 0.04419 LOS LC3 1 0.34466 0.04564 LOS LC2 1 0.33762 0.04118 LP2 LP2 1 0.39596 0.02382 LP2 LP3 1 0.396 0.02909 LP2 LC3 1 0.39599 0.03005 LP2 LC2 1 0.38789 0.02712 LP3 LP3 1 0.39601 0.03556 LP3 LC3 1 0.396 0.03673 LP3 LC2 1 0.38792 0.03313 LC3 LC3 1 0.39599 0.03793 LC3 LC2 1 0.38791 0.03422 LC2 LC2 1 0.37998 0.03088 [ dihedraltypes ] LP2 LP2 3 9.2789 12.156 -13.120 -3.0597 26.240 -31.495 LH2 LH2 3 9.2789 12.156 -13.120 -3.0597 26.240 -31.495 the dmpcopls.itp is: [ moleculetype ] ; name nrexcl DMPC 3 [ atoms ] ; id atype resnr resname aname cgnr charge mass 1 LC3 1 DMPC CN1 0 0.4000 15.0350 2 LC3 1 DMPC CN2 0 0.4000 15.0350 3 LC3 1 DMPC CN3 0 0.4000 15.0350 4 LNL 1 DMPC NTM 0 -0.5000 14.0067 5 LH2 1 DMPC CA 0 0.3000 14.0270 6 LC2 1 DMPC CB 1 0.4000 14.0270 7 LOS 1 DMPC OA 1 -0.8000 15.9994 8 LP 1 DMPC P 1 1.7000 30.9738 9 LOM 1 DMPC OB 1 -0.8000 15.9994 10 LOM 1 DMPC OC 1 -0.8000 15.9994 11 LOS 1 DMPC OD 1 -0.7000 15.9994 12 LC2 1 DMPC CC 2 0.4000 14.0270 13 LH1 1 DMPC CD 2 0.3000 13.0190 14 LOS 1 DMPC OE 2 -0.7000 15.9994 15 LC 1 DMPC C2A 2 0.7000 12.0110 16 LO 1 DMPC OF 2 -0.7000 15.9994 17 LP2 1 DMPC C2B 3 0.0000 14.0270 18 LP2 1 DMPC C2C 4 0.0000 14.0270 19 LP2 1 DMPC C2D 5 0.0000 14.0270 20 LP2 1 DMPC C2E 6 0.0000 14.0270 21 LP2 1 DMPC C2F 7 0.0000 14.0270 22 LP2 1 DMPC C2G 8 0.0000 14.0270 23 LP2 1 DMPC C2H 9 0.0000 14.0270 24 LP2 1 DMPC C2I 10 0.0000 14.0270 25 LP2 1 DMPC C2J 11 0.0000 14.0270 26 LP2 1 DMPC C2K 12 0.0000 14.0270 27 LP2 1 DMPC C2L 13 0.0000 14.0270 28 LP2 1 DMPC C2M 14 0.0000 14.0270 29 LP3 1 DMPC C2N 15 0.0000 15.0350 30 LC2 1 DMPC CE 18 0.5000 14.0270 31 LOS 1 DMPC OG 18 -0.7000 15.9994 32 LC 1 DMPC C1A 18 0.8000 12.0110 33 LO 1 DMPC OH 18 -0.6000 15.9994 34 LP2 1 DMPC C1B 19 0.0000 14.0270 35 LP2 1 DMPC C1C 20 0.0000 14.0270 36 LP2 1 DMPC C1D 21 0.0000 14.0270 37 LP2 1 DMPC C1E 22 0.0000 14.0270 38 LP2 1 DMPC C1F 23 0.0000 14.0270 39 LP2 1 DMPC C1G 24 0.0000 14.0270 40 LP2 1 DMPC C1H 25 0.0000 14.0270 41 LP2 1 DMPC C1I 26 0.0000 14.0270 42 LP2 1 DMPC C1J 27 0.0000 14.0270 43 LP2 1 DMPC C1K 28 0.0000 14.0270 44 LP2 1 DMPC C1L 29 0.0000 14.0270 45 LP2 1 DMPC C1M 30 0.0000 14.0270 46 LP3 1 DMPC C1N 31 0.0000 15.0350 [ bonds ] ; ai aj func b0 cb 1 4 1 0.14700E+00 0.37660E+06 2 4 1 0.14700E+00 0.37660E+06 3 4 1 0.14700E+00 0.37660E+06 4 5 1 0.14700E+00 0.37660E+06 5 6 1 0.15300E+00 0.33470E+06 6 7 1 0.14300E+00 0.33470E+06 7 8 1 0.16100E+00 0.25100E+06 8 9 1 0.14800E+00 0.33470E+06 8 10 1 0.14800E+00 0.33470E+06 8 11 1 0.16100E+00 0.25100E+06 11 12 1 0.14300E+00 0.33470E+06 12 13 1 0.15300E+00 0.33470E+06 13 14 1 0.14300E+00 0.33470E+06 14 15 1 0.13600E+00 0.37660E+06 15 16 1 0.12300E+00 0.50210E+06 15 17 1 0.15300E+00 0.33470E+06 17 18 1 0.15300E+00 0.33470E+06 18 19 1 0.15300E+00 0.33470E+06 19 20 1 0.15300E+00 0.33470E+06 20 21 1 0.15300E+00 0.33470E+06 21 22 1 0.15300E+00 0.33470E+06 22 23 1 0.15300E+00 0.33470E+06 23 24 1 0.15300E+00 0.33470E+06 24 25 1 0.15300E+00 0.33470E+06 25 26 1 0.15300E+00 0.33470E+06 26 27 1 0.15300E+00 0.33470E+06 27 28 1 0.15300E+00 0.33470E+06 28 29 1 0.15300E+00 0.33470E+06 13 30 1 0.15300E+00 0.33470E+06 30 31 1 0.14300E+00 0.33470E+06 31 32 1 0.13600E+00 0.37660E+06 32 33 1 0.12300E+00 0.50210E+06 32 34 1 0.15300E+00 0.33470E+06 34 35 1 0.15300E+00 0.33470E+06 35 36 1 0.15300E+00 0.33470E+06 36 37 1 0.15300E+00 0.33470E+06 37 38 1 0.15300E+00 0.33470E+06 38 39 1 0.15300E+00 0.33470E+06 39 40 1 0.15300E+00 0.33470E+06 40 41 1 0.15300E+00 0.33470E+06 41 42 1 0.15300E+00 0.33470E+06 42 43 1 0.15300E+00 0.33470E+06 43 44 1 0.15300E+00 0.33470E+06 44 45 1 0.15300E+00 0.33470E+06 45 46 1 0.15300E+00 0.33470E+06 [ pairs ] ;Here is the first copy ai aj func c6 c12 1 6 1 2 6 1 3 6 1 4 7 1 5 8 1 6 9 1 6 10 1 6 11 1 7 12 1 8 13 1 9 12 1 10 12 1 11 14 1 11 30 1 12 15 1 12 31 1 13 16 1 13 17 1 13 32 1 14 18 1 14 31 1 15 19 1 15 30 1 16 18 1 30 33 1 30 34 1 31 35 1 32 36 1 33 35 1 ; Here is the second copy. Only use this with the modified LJ-14 epsilon values 1 6 1 2 6 1 3 6 1 4 7 1 5 8 1 6 9 1 6 10 1 6 11 1 7 12 1 8 13 1 9 12 1 10 12 1 11 14 1 11 30 1 12 15 1 12 31 1 13 16 1 13 17 1 13 32 1 14 18 1 14 31 1 15 19 1 15 30 1 16 18 1 30 33 1 30 34 1 31 35 1 32 36 1 33 35 1 [ angles ] ; ai aj ak func t0 ct 1 4 2 1 0.10950E+03 0.46020E+03 1 4 3 1 0.10950E+03 0.46020E+03 1 4 5 1 0.10950E+03 0.46020E+03 2 4 3 1 0.10950E+03 0.46020E+03 2 4 5 1 0.10950E+03 0.46020E+03 3 4 5 1 0.10950E+03 0.46020E+03 4 5 6 1 0.10950E+03 0.46020E+03 5 6 7 1 0.10950E+03 0.46020E+03 6 7 8 1 0.12000E+03 0.39750E+03 7 8 9 1 0.10950E+03 0.39750E+03 7 8 10 1 0.10950E+03 0.39750E+03 7 8 11 1 0.10300E+03 0.39750E+03 9 8 10 1 0.12000E+03 0.58580E+03 9 8 11 1 0.10950E+03 0.39750E+03 10 8 11 1 0.10950E+03 0.39750E+03 8 11 12 1 0.12000E+03 0.39750E+03 11 12 13 1 0.11100E+03 0.46020E+03 12 13 14 1 0.10950E+03 0.46020E+03 12 13 30 1 0.10950E+03 0.46020E+03 14 13 30 1 0.10950E+03 0.46020E+03 13 14 15 1 0.12000E+03 0.41840E+03 14 15 16 1 0.12400E+03 0.50210E+03 14 15 17 1 0.11500E+03 0.50210E+03 16 15 17 1 0.12100E+03 0.50210E+03 15 17 18 1 0.11100E+03 0.46020E+03 17 18 19 1 0.11100E+03 0.46020E+03 18 19 20 1 0.11100E+03 0.46020E+03 19 20 21 1 0.11100E+03 0.46020E+03 20 21 22 1 0.11100E+03 0.46020E+03 21 22 23 1 0.11100E+03 0.46020E+03 22 23 24 1 0.11100E+03 0.46020E+03 23 24 25 1 0.11100E+03 0.46020E+03 24 25 26 1 0.11100E+03 0.46020E+03 25 26 27 1 0.11100E+03 0.46020E+03 26 27 28 1 0.11100E+03 0.46020E+03 27 28 29 1 0.11100E+03 0.46020E+03 13 30 31 1 0.11100E+03 0.46020E+03 30 31 32 1 0.12000E+03 0.41840E+03 31 32 33 1 0.12400E+03 0.50210E+03 31 32 34 1 0.11500E+03 0.50210E+03 33 32 34 1 0.12100E+03 0.50210E+03 32 34 35 1 0.11100E+03 0.46020E+03 34 35 36 1 0.11100E+03 0.46020E+03 35 36 37 1 0.11100E+03 0.46020E+03 36 37 38 1 0.11100E+03 0.46020E+03 37 38 39 1 0.11100E+03 0.46020E+03 38 39 40 1 0.11100E+03 0.46020E+03 39 40 41 1 0.11100E+03 0.46020E+03 40 41 42 1 0.11100E+03 0.46020E+03 41 42 43 1 0.11100E+03 0.46020E+03 42 43 44 1 0.11100E+03 0.46020E+03 43 44 45 1 0.11100E+03 0.46020E+03 44 45 46 1 0.11100E+03 0.46020E+03 [ dihedrals ] ; These are the improper dihedrals ; ai aj ak al func q0 cq 13 14 30 12 2 0.35264E+02 0.33470E+03 15 14 17 16 2 0.00000E+00 0.16740E+03 32 31 34 33 2 0.00000E+00 0.16740E+03 [ dihedrals ] ; These are the proper dihedrals ; ai aj ak al func phi0 cphi mult 1 4 5 6 1 0.00000E+00 0.37656E+01 3 4 5 6 7 1 0.00000E+00 0.58576E+01 3 5 6 7 8 1 0.00000E+00 0.37656E+01 3 6 7 8 11 1 0.00000E+00 0.10460E+01 3 7 8 11 12 1 0.00000E+00 0.10460E+01 3 8 11 12 13 1 0.00000E+00 0.37656E+01 3 11 12 13 14 1 0.00000E+00 0.20920E+01 2 12 13 14 15 1 0.00000E+00 0.37656E+01 3 13 14 15 17 1 0.18000E+03 0.16736E+02 2 14 15 17 18 1 0.00000E+00 0.41840E+00 6 15 17 18 19 1 0.00000E+00 0.58576E+01 3 17 18 19 20 3 18 19 20 21 3 19 20 21 22 3 20 21 22 23 3 21 22 23 24 3 22 23 24 25 3 23 24 25 26 3 24 25 26 27 3 25 26 27 28 3 26 27 28 29 3 14 13 30 31 1 0.00000E+00 0.20920E+01 2 13 30 31 32 1 0.00000E+00 0.37656E+01 3 30 31 32 34 1 0.18000E+03 0.16736E+02 2 31 32 34 35 1 0.00000E+00 0.41840E+00 6 32 34 35 36 1 0.00000E+00 0.58576E+01 3 34 35 36 37 3 35 36 37 38 3 36 37 38 39 3 37 38 39 40 3 38 39 40 41 3 39 40 41 42 3 40 41 42 43 3 41 42 43 44 3 42 43 44 45 3 43 44 45 46 3 #ifdef DMPC_POSRES ; position restraints for DMPC [ position_restraints ] ; atom type fx fy fz 1 1 1000.0 1000.0 1000.0 2 1 1000.0 1000.0 1000.0 3 1 1000.0 1000.0 1000.0 4 1 1000.0 1000.0 1000.0 5 1 1000.0 1000.0 1000.0 6 1 1000.0 1000.0 1000.0 7 1 1000.0 1000.0 1000.0 8 1 1000.0 1000.0 1000.0 9 1 1000.0 1000.0 1000.0 10 1 1000.0 1000.0 1000.0 11 1 1000.0 1000.0 1000.0 12 1 1000.0 1000.0 1000.0 13 1 1000.0 1000.0 1000.0 14 1 1000.0 1000.0 1000.0 15 1 1000.0 1000.0 1000.0 16 1 1000.0 1000.0 1000.0 17 1 1000.0 1000.0 1000.0 18 1 1000.0 1000.0 1000.0 19 1 1000.0 1000.0 1000.0 20 1 1000.0 1000.0 1000.0 21 1 1000.0 1000.0 1000.0 22 1 1000.0 1000.0 1000.0 23 1 1000.0 1000.0 1000.0 24 1 1000.0 1000.0 1000.0 25 1 1000.0 1000.0 1000.0 26 1 1000.0 1000.0 1000.0 27 1 1000.0 1000.0 1000.0 28 1 1000.0 1000.0 1000.0 29 1 1000.0 1000.0 1000.0 30 1 1000.0 1000.0 1000.0 31 1 1000.0 1000.0 1000.0 32 1 1000.0 1000.0 1000.0 33 1 1000.0 1000.0 1000.0 34 1 1000.0 1000.0 1000.0 35 1 1000.0 1000.0 1000.0 36 1 1000.0 1000.0 1000.0 37 1 1000.0 1000.0 1000.0 38 1 1000.0 1000.0 1000.0 39 1 1000.0 1000.0 1000.0 40 1 1000.0 1000.0 1000.0 41 1 1000.0 1000.0 1000.0 42 1 1000.0 1000.0 1000.0 43 1 1000.0 1000.0 1000.0 44 1 1000.0 1000.0 1000.0 45 1 1000.0 1000.0 1000.0 46 1 1000.0 1000.0 1000.0 #endif Is my 1-4 scaling correct? I am confused about my topologies. Please help. Ms. Anindita Gayen C/O Dr. Chaitali Mukhopadhyay Senior Research Fellow University of Calcutta Best Jokes, Best Friends, Best Food and more. Go to http://in.promos.yahoo.com/groups/bestofyahoo/ _______________________________________________ gmx-users mailing list gmx-users@gromacs.org http://www.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/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/mailing_lists/users.php