[gmx-users] Is Gromos43a2X problem?

[nanyu101]

Dear Dr.Erik Lindahl,
  Sorry to write to you so many letters.
  I have used your Gromos43a2X force field to simulate the DPPC bilayer for my polyester ion channel.But I have always met some problem in NVT and NPT running.I suppose my minimization is very fine.The minimization information was listed as follows:
Steepest descent methods:
Steepest Descents converged to 250 in 68 steps
Potential Energy  = -2.50687e+05
Maximum force:  2.16913e+02

Conjugate gradient methods:
Conjugate Gradients converged to 250 in 1028 steps
Potential Energy  = -2.50634e+05
Maximum force:  2.49903e+02

But when I use minimized structure to run NVT,there are always some problem happened. I think there are some big forces in my lipid bilayer, but how can they exist? Would you like to give me some suggestion? The more detailed log file is in my attachment.


Some of system message:
Step 519, time 1.038 (ps)  LINCS WARNING
relative constraint deviation after LINCS:
max 631648.500000 (between atoms 2218 and 2219) rms 21577.753906
bonds that rotated more than 30 degrees:
 atom 1 atom 2  angle  previous, current, constraint length
    137    138   63.5    0.1530   0.0639      0.1530
    138    139   90.0    0.1530   2.8165      0.1530
    139    140   90.0    0.1529   2.7698      0.1530
   1811   1812   32.9    0.1562   0.1320      0.1430
..................................
 1819   1820   90.2   37.1000 144.3615      0.1530
   1820   1821   89.9  169.8499 825.1577      0.1530
   1821   1822   87.3  434.7396 631.8299      0.1530
   1822   1823   90.3  1408.7289 3796.5017      0.1530
   1823   1824   90.0  4800.0195 32105.7539      0.1530
   1824   1825   90.0  33271.7930 90467.0625      0.1530
   1825   1826   90.0  96110.5234 17859.9531      0.1530
   1826   1827   89.6  13803.7080 17890.7500      0.1530
   1827   1828   91.9  23237.4902 19084.4531      0.1530
   1828   1829   91.5  24435.0898 25381.4668      0.1530
   1829   1830   91.0  59897.6328 67631.1953      0.1530
   1830   1831   91.4  126750.7031 22268.1074      0.1530
   1832   1833   40.5    0.1510   0.1512      0.1430
   2012   2013   92.4    0.1840   1.4619      0.1530
............................

Wrote pdb files with previous and current coordinates
Fatal error: ci = -2147483648 should be in 0 .. 342 [FILE nsgrid.c, LINE 210]




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