[gmx-users] Radius of gyration

[独角仙]

Dear gromacs experts,
      I tried to analysis the Radius of gyration of a polymer. But I found the result of first frame was always very different.
      Then I installed different vesions of gmx with or without mpi.
      And I got different results.  
      So I used the first tutorial on http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin/gmx-tutorials/lysozyme/index.html as a example.
      I import the mases from the top file to matlab, and got the positions via vmd.
      It seems only 5.0.4 vesion without mpi get the correct result. While all the others have the same wrong number.
      But when I copy the file to another machine, I get another different false result.

      So where the problem come from? 

Thanks,
Kangjie Lv
489524021 at qq.com

------------------------------------
My result:(protein rg of frame 0)
vesion 4.6.7
with mpi:
         0     1.36815     1.16912     1.34953     0.74539
        10     1.38857     1.17871     1.38217    0.745979
withoutmpi:
         0     1.36815     1.16912     1.34953     0.74539
        10     1.38857     1.17871     1.38217    0.745979
vesion 5.0.4
with mpi: 
         0     1.36815     1.16912     1.34953     0.74539
        10     1.38857     1.17871     1.38217    0.745979
withoutmpi: 
         0     1.40022     1.19943     1.02439     1.19718
        10     1.41136     1.20202     1.04328      1.2044
from matlab:  
         0     14.0022
        10     14.1135
another machine(has 64 cores):
vesion 5.0.4
with mpi (the first frame always false using different -b flags)
         0      1.4657     1.38007     1.12533     1.06095
        10     2.15321     1.45292     1.74791     2.02645
without mpi
         0     1.40022     1.19943     1.02439     1.19718
        10     1.41136     1.20202     1.04328      1.2044

all files here
http://pan.baidu.com/s/1hq9yFsw