Strange behavior of CONStraints statement

Ajay Royyuru ajay at mskcc.org
Fri Jan 12 14:39:42 EST 1996


We note an apparent discrepancy in the behavior of CONStraints statement.

Lets say the system consists of segments A and B. The VDW could be
broken into A - A, B - B, and A - B. To neglect A - B, I try

CONSTRAINTS 
  INTERACTION (ALL) (ALL) WEIGHTS VDW 1.0 END
  INTERACTION (SEGI A) (SEGI B) WEIGHTS VDW 0.0 END
END

ENERGY END

Still computes the vdw  A - B and includes it in the reported VDW !

Whereas, 

CONSTRAINTS 
  INTERACTION (ALL) (ALL) WEIGHTS VDW 0.0 END
  INTERACTION (SEGI A) (SEGI A) WEIGHTS VDW 1.0 END
  INTERACTION (SEGI B) (SEGI B) WEIGHTS VDW 1.0 END
END

ENERGY END

does neglect vdw A - B.

In the systems that I have tested, A and B are different molecules. But
that shouldn't matter.

Its X-plor 3.1f, on SGI IRIX 5.3 and 6.0.1.

Is this a known problem, or am I doing something wrong ?
TIA.

+------------------------------------------------------------------+
| Ajay Kumar Royyuru, PhD                 | Tel +1 (212) 639 7225  |
| Memorial Sloan-Kettering Cancer Center  | Fax +1 (212) 717 3066  |
| Box 557                                 |                        |
| 1275 York Avenue                        | mailto:ajay at mskcc.org  |
| New York NY 10021                       |                        |
+------------------------------------------------------------------+



More information about the X-plor mailing list