Hi,
I am using TI with soft-core to study relative binding free energy. I followed the tutorial and tested several additional cases with T4 lysozyme by making small changes in the ligand. Everything went well.
Problem happened when I tried to "mutant" a protein residue (V111T) with the same ligand (benzene). The "charge off" and "charge on" parts have no problem since the v0 and v1 are still the "same" complex and only the charges are changing. The "vdw" part with soft-core caused problem. In the initial minimization step (SD with only 2 processors), the "sander.MPI" process hangs without producing any results. Both processes did not crash, just running without updating output files or producing the "mdinfo" file.  I put the two output files in attachments.
The command I started the run was:
openmpirun_wrapper sander.MPI -ng 2 -groupfile group_mini_L0.5
"groupfile group_mini_L0.5" contains:
-O -i VDW_mdin_mini_v0_L0.5 -o VDW_mdout_mini_v0_L0.5 -p T4_comp.prm -c T4_comp.rst -r T4_comp_mini_v0_0.5.rst
-O -i VDW_mdin_mini_v1_L0.5 -o VDW_mdout_mini_v1_L0.5 -p T4_V111T_comp.prm -c T4_V111T_comp.rst -r T4_V111T_comp_mini_v1_0.5.rst
The difference in the two input parameter/coordinate files are only at the residue 111. The ligand, water and counter ions remain the same. The following are the difference in pdb format. Of course the atom numbering is different after residue 111.
"original"
ATOM   1736  N   VAL   111      -6.428   0.036  -6.083  1.00  0.00
ATOM   1737  H   VAL   111      -6.147  -0.063  -5.118  1.00  0.00
ATOM   1738  CA  VAL   111      -6.477  -1.161  -6.915  1.00  0.00
ATOM   1739  HA  VAL   111      -5.773  -1.044  -7.739  1.00  0.00
ATOM   1740  CB  VAL   111      -6.057  -2.343  -6.088  1.00  0.00
ATOM   1741  HB  VAL   111      -6.796  -2.538  -5.310  1.00  0.00
ATOM   1742  CG1 VAL   111      -5.954  -3.559  -7.009  1.00  0.00
ATOM   1743 1HG1 VAL   111      -5.215  -3.365  -7.786  1.00  0.00
ATOM   1744 2HG1 VAL   111      -5.650  -4.430  -6.429  1.00  0.00
ATOM   1745 3HG1 VAL   111      -6.924  -3.750  -7.469  1.00  0.00
ATOM   1746  CG2 VAL   111      -4.691  -2.036  -5.519  1.00  0.00
ATOM   1747 1HG2 VAL   111      -4.748  -1.140  -4.901  1.00  0.00
ATOM   1748 2HG2 VAL   111      -4.354  -2.875  -4.911  1.00  0.00
ATOM   1749 3HG2 VAL   111      -3.986  -1.871  -6.334  1.00  0.00
ATOM   1750  C   VAL   111      -7.821  -1.439  -7.544  1.00  0.00
ATOM   1751  O   VAL   111      -7.926  -1.788  -8.734  1.00  0.00
"V111T"
ATOM   1736  N   THR   111      -6.428   0.036  -6.083  1.00  0.00
ATOM   1737  H   THR   111      -6.147  -0.063  -5.118  1.00  0.00
ATOM   1738  CA  THR   111      -6.477  -1.161  -6.915  1.00  0.00
ATOM   1739  HA  THR   111      -5.773  -1.044  -7.739  1.00  0.00
ATOM   1740  CB  THR   111      -6.057  -2.343  -6.088  1.00  0.00
ATOM   1741  HB  THR   111      -5.819  -2.008  -5.078  1.00  0.00
ATOM   1742  CG2 THR   111      -7.209  -3.362  -6.026  1.00  0.00
ATOM   1743 1HG2 THR   111      -6.905  -4.219  -5.426  1.00  0.00
ATOM   1744 2HG2 THR   111      -7.456  -3.694  -7.034  1.00  0.00
ATOM   1745 3HG2 THR   111      -8.084  -2.895  -5.573  1.00  0.00
ATOM   1746  OG1 THR   111      -4.900  -2.956  -6.667  1.00  0.00
ATOM   1747 1HG  THR   111      -5.124  -3.277  -7.641  1.00  0.00
ATOM   1748  C   THR   111      -7.821  -1.439  -7.544  1.00  0.00
ATOM   1749  O   THR   111      -7.926  -1.788  -8.734  1.00  0.00
I tried to run this with different memory setup 1.75Gb or 3.5Gb. There is no difference. Also, I tried to bypass minimization and started MD directly. Similar problem encountered. The "sander.MPI" tested was rebuilt on Feb 24, 2009 with latest patches.
 I can provide the files to run the jobs if someone would like to take a look at the problem.
Thanks in advance!
Regards,
Jeff
Xiaohui (Jeff) Jiang, Ph.D.
Research Scientist
Phone: (301) 619-1986
Fax: (301) 619-1983
DoD Biotechnology HPC Software Applications Institute
BHSAI/MRMC, ATTN: MCMR-TT
Building 363 Miller Drive
Fort Detrick, MD 21702-5012
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Received on Fri Mar 06 2009 - 01:10:55 PST