<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman,new york,times,serif;font-size:12pt"><div>Hi everybody!<br><br>I made .top file for oxalic acid (OPLSAA ff), and energy mininization goes normally, but molecule becomes distorted after md in vacuo at 50 K (0K is still ok). I cannot understand what I'm doing wrong. <br><br>Thanks in advance!<br><br>Liliya<br><br>oxalic_acid<br> 8<br> 1OXD C1 1 7.752 9.727 5.820<br> 1OXD O_31 2 8.626 8.893 5.820<br> 1OXD OH1 3 8.016 11.053 5.820<br> 1OXD HO1 4 9.001 11.076
5.820<br> 1OXD C2 5 6.213 9.479 5.820<br> 1OXD O_32 6 5.706 8.379 5.820<br> 1OXD OH2 7 5.534 10.649 5.820<br> 1OXD HO2 8 6.179 11.393 5.820<br> 14.25703 13.44165 11.64081 0.00000 0.00000 4.75234 0.00000 -4.75234 6.72083<br><br><br>;<br>; Topology file for oxalic acid<br>; Created by: Liliya Shamova<br>; e-mail: lshamova@yahoo.com<br><br>; Include forcefield parameters<br>#include "ffoplsaa.itp"<br><br>[ moleculetype ]<br>;
Name nrexcl<br>OXD 3<br><br>[ atoms ]<br>; nr type resnr residue atom cgnr charge mass typeB chargeB massB<br> 1 opls_267 1 OXD C1 1 0.520 12.011 ; qtot <br> 2 opls_269 1 OXD O_31 1 -0.440 15.9994 ; qtot
<br> 3 opls_268 1 OXD OH1 1 -0.530 15.9994 ; qtot <br> 4 opls_270 1 OXD HO1 1 0.450 1.008 ; qtot 0<br> 5 opls_267 1 OXD C2 2 0.520 12.011 ; qtot <br> 6 opls_269 1 OXD O_32 2 -0.440 15.9994 ;
qtot <br> 7 opls_268 1 OXD OH2 2 -0.530 15.9994 ; qtot <br> 8 opls_270 1 OXD HO2 2 0.450 1.008 ; qtot <br> <br>[ bonds ]<br>; ai aj funct c0 c1 c2 c3<br> 1 2 1 <br>
1 3 1 <br> 3 4 1<br> 1 5 1<br> 5 6 1<br> 5 7 1<br> 7 8 1<br><br>[ pairs ]<br>; ai aj funct c0 c1 c2 c3<br>; 2 4 1<br>; 2 6 1<br>;
4 5 1<br> 2 7 1<br>; 1 8 1<br> 7 3 1<br> 3 6 1<br>; 6 8 1<br>; 7 4 1<br>; 3 8 1<br> <br>[ angles ]<br>; ai aj ak funct c0 c1 c2
c3<br> 2 1 3 1 <br> 1 3 4 1<br> 2 1 5 1<br> 1 5 6 1<br> 6 5 7 1<br> 5 7 8 1<br>; 3 1 5 1<br>; 1 5 7 1<br> <br>[ dihedrals ]<br>; ai aj ak al
funct c0 c1 c2 c3 c4 c5<br> 2 1 3 4 3; 5.5 0 -5.5 0 0 0
<br>; 2 1 5 6 3 ; 4 -0.8 -3.2 0 0 0<br>; 2 1 5 7 3 ;<br> 6 5 7 8 3 ; 5.5
0 -5.5 0 0 0 <br> 1 5 7 8 3 ; 7 -1.5 -5.5 0 0 0 <br>; 3 1 5
7 3 ;<br>; 3 1 5 6 3 ;<br> 4 3 1 5 3 ; 7 -1.5 -5.5 0 0 0 <br><br>;#define improper_CB14_CB12_CL4_CB16 180 4.6024 2<br>;#define improper_CB15_CB13_CL1_CB16 180 4.6024 2<br>; Include Position restraint
file<br>;#ifdef POSRES<br>;#include "posre.itp"<br>;#endif<br><br>; Include water topology<br>;#ifdef FLEX_SPC<br>;#include "flexspc.itp"<br>;#else<br>;#include "spc.itp"<br>;#endif<br><br>;#ifdef POSRES_WATER<br>; Position restraint for each water oxygen<br>;[ position_restraints ]<br>; i funct fcx fcy fcz<br>; 1 1 1000 1000 1000<br>;#endif<br><br>[ system ]<br>; Name<br>oxalic_acid <br><br>[ molecules ]<br>; Compound #mols<br>OXD 1<br><br>;<br>; User spoel (236)<br>; Wed Nov 3 17:12:44 1993<br>; Input
file<br>;<br>title = full 50 K<br>cpp = /usr/bin/cpp<br>;define = -DPOSRES<br>constraints = none<br>integrator = md<br>dt = 0.002 ; ps !<br>nsteps = 10000 ; total 20 ps.<br>nstcomm = 10 ; frequency for center of mass motion
removal<br>comm_mode = Angular<br>nstxout = 200 ; to write coordinates<br>nstvout = 1000 ; velocities<br>nstfout = 0 ; forces<br>nstlog = 100
;<br>nstenergy = 100<br>nstlist = 0<br>ns_type = simple<br>pbc = no<br>rlist = 0<br>rcoulomb = 0<br>rvdw = 0<br>;SHAKE properties<br>;constraint_algorithm= SHAKE<br>;shake_tol = 0.0001<br>; Berendsen temperature coupling is on in one
group<br>Tcoupl = berendsen<br>tc_grps = System<br>tau_t = 0.1<br>ref_t = 50<br>; Energy monitoring<br><br>; Pressure coupling is not on<br>Pcoupl = no<br>tau_p = 0.5<br>compressibility = 4.5e-5<br>ref_p = 1.0<br>; Generate velocites is on at 50 K.<br>gen_vel
= yes<br>gen_temp = 50.0<br>gen_seed = 173529<br><br></div></div><br>
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