AMBER Archive (2005)

Subject: AMBER: Using OPLS atom types

From: Lorna Stimson (lorna.stimson_at_gmail.com)
Date: Tue Nov 22 2005 - 10:18:48 CST

Hi,

I am trying to use OPLS atom type in amber, i have altered the
opls_parm.dat file to the new format and removed the non-bonded STDU
and STUB vdw parameters and everything seems OK, except that the "AC"
flag which specifies c6-c12 style params instead of "RE" for radius,
thus the vdw energy is ridiculous.

Is there another flag to specify the format of the vdw parameters
which must be set in leap?

Does anyone have experience using other than the "RE" flag which may
help me track down the problem?

Below is the tail of my parm file.

Thanks,

Lorna

 C2-OS-P -O2 3 0.75 0. 3.
    From X -OS-P -X
OS-C2-CH-OS 1 1.0 0. -3.
OS-C2-CH-OS 1 0.5 0. 2.
OS-P -OS-C2 1 .25 0. -3.
OS-P -OS-C2 1 .75 0. 2.
C2-C2-C -OS 2 0.0 180. 3.
  From X -C2-C -X
C2-C2-C -O 2 0.0 180. 3.
  From X -C2-C -X
CH-C2-OS-P 1 1.45 0. 3.
  From X -C2-OS-X
C2-C2-OS-P 1 1.45 0. 3.
  From X -C2-OS-X
CH-C2-OS-C 1 1.45 0. 3.
  From X -C2-OS-X
O -C -OS-C2 1 2.25 180. -2.
 Gdansk, M.P.-G. 20.06.'97
O -C -OS-C2 1 2.70 180. 1.
 Gdansk, M.P.-G. 20.06.'97

OS-CH-C2-C2 3 14.0 180. 3.
From X -CH-C2-X

OPLS AC
  CH 2901000.0 963.5
  C3 8171500.0 2286.9
  C2 5934600.0 1673.7
  C 3248100.0 1168.0
  OS 361380.0 495.7
  O 380000.0 565.0
  O2 380000.0 565.0
  N3 944300.0 801.3
  P 7113043.3 2667.0
  HW 0.0 0.0 TIP3P water model
  OW 582000.0 595.0 TIP3P water model
  XE 23871780.0 6430.0 From opls.info
xe 3.935 0.4330 => 6.430079e+03 2.387178e+07

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