[gmx-users] Polymer exploding

[kitty ji]

Polymer exploding

Hi:

I built Poly(vinyl methyl ether) (PVME)with the alkane and ether paramters in OPLS force field. Its repeats number is 22. Tip5p was set as solvent.

The initial density of PVME melt is 0.8, 1.0 and 1.05 g/cm3. Its experimental value is 1.05 g/cm3.The initial density of PVME solution is 1.0 g/cm3. The concentration is 20% and 60%.

The plan runing process is l-bfgs, NVT and NPT.

However in NVT running, the 3 melt and 60% system all exploding. With the help from google, I increase the tau_t from 0.1 to 0.5. A serial of begin structures were prepared. But it is no helpful. While the 20% model is ok. 

What is the possible error? How can it fix it? 

Bellow is the md.log file around the exploding time point.

   Step           Time         Lambda
          14140       28.28000        0.00000

   Energies (kJ/mol)
           Bond          Angle Ryckaert-Bell.          LJ-14     Coulomb-14
    1.23776e+04    1.97954e+04    1.57445e+04    6.49124e+03   -5.38649e+04
        LJ (SR)  Disper. corr.   Coulomb (SR)      Potential    Kinetic En.
   -1.32445e+04   -1.20529e+03    5.64457e+04    4.25397e+04    3.30808e+04
   Total Energy    Temperature Pressure (bar)
    7.56204e+04    2.98767e+02   -3.82251e+02

           Step           Time         Lambda
          14150       28.30000        0.00000

   Energies (kJ/mol)
           Bond          Angle Ryckaert-Bell.          LJ-14     Coulomb-14
    1.24969e+04    1.97987e+04    1.57022e+04    6.37298e+03   -5.38467e+04
        LJ (SR)  Disper. corr.   Coulomb (SR)      Potential    Kinetic En.
   -1.22941e+04   -1.20529e+03    5.64734e+04    4.34981e+04    4.72135e+04
   Total Energy    Temperature Pressure (bar)
    9.07116e+04    4.26405e+02    7.73594e+02

           Step           Time         Lambda
          14160       28.32000        0.00000

   Energies (kJ/mol)
           Bond          Angle Ryckaert-Bell.          LJ-14     Coulomb-14
    4.17034e+16    2.76374e+04    1.57162e+04    6.48244e+03   -5.37968e+04
        LJ (SR)  Disper. corr.   Coulomb (SR)      Potential    Kinetic En.
   -1.33165e+04   -1.20529e+03    5.64059e+04    4.17034e+16    3.87149e+16
   Total Energy    Temperature Pressure (bar)
    8.04183e+16    3.49651e+14   -3.11470e+14

           Step           Time         Lambda
          14170       28.34000        0.00000

   Energies (kJ/mol)
           Bond          Angle Ryckaert-Bell.          LJ-14     Coulomb-14
    4.17033e+16    2.76378e+04    1.57140e+04    6.48244e+03   -5.37968e+04
        LJ (SR)  Disper. corr.   Coulomb (SR)      Potential    Kinetic En.
   -1.33165e+04   -1.20529e+03    5.64060e+04    4.17033e+16    3.87149e+16
   Total Energy    Temperature Pressure (bar)
    8.04182e+16    3.49651e+14   -3.11456e+14

           Step           Time         Lambda
          14180       28.36000        0.00000

   Energies (kJ/mol)
           Bond          Angle Ryckaert-Bell.          LJ-14     Coulomb-14
    4.17033e+16    2.76378e+04    1.57140e+04    6.48244e+03   -5.37968e+04
        LJ (SR)  Disper. corr.   Coulomb (SR)      Potential    Kinetic En.
   -1.33165e+04   -1.20529e+03    5.64060e+04    4.17033e+16    3.87149e+16
   Total Energy    Temperature Pressure (bar)
    8.04182e+16    3.49651e+14   -3.11456e+14


*************************************************
Ji Qing
Institute of Chemistry, Chinese Academy of Sciences
Tel: 0086-10-62562894  ，82618423
*************************************************
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://maillist.sys.kth.se/pipermail/gromacs.org_gmx-users/attachments/20070215/61b28011/attachment.html>