[gmx-users] Re: fudgeQQ (again ...) and fudgeLJ
qiaobf at gmail.com
Sat Dec 9 19:50:28 CET 2006
I have just tested the fudgeQQ and fudgeLJ, and found one problem:
I use the ffoplsaa force field, and add the atoms I used.(in the
ffolpsaanb.itp file, there is no [pairtype] section, and I only add the atom
; name bond_type mass charge ptype
opls_966 CT 6 12.01100 0 A 3.40000e-01
I write my .itp file by hand, in which in the [ pairs] section, I write the
pairs and the function, but don't give the values of C6 and C12, that is,
[ pairs ]
; ai aj fu c6 c12
1 5 1
1 6 1
In the ffoplsaa.itp, I used
; nbfunc comb-rule gen-pairs fudgeLJ fudgeQQ
1 2 yes 0.5 0.8333
I used different values of fudgeLJ and fudgeQQ in the 4 tests, see the
fudgeLJ fudgeQQ result (from .log file):
1. 0.5 0.5
2 1 1
3. 0.25 0.25
4. 0.5 0.8333
The problem is that the LJ-14 doesn't change with the scaling factor of
Does it mean that I must give the C6 and C12 in the .itp file? If yes,
should the C6 and C12 scaled by the scaling factor (0.5) and "gen-pairs =
no; fudgeLJ=1" ?
Another question is that in the .log file, what is the "Disper. corr."?
What is the difference between it and the 1-4 interacion?
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