[gmx-users] Re: using different force fields

[Graham Smith]

> If you want a real all-atom force field you have to use OPLS
> (preferbly with TIP4P water). 

BTW the provided tip4pgmx.itp file needs a bit of reformatting -
I copied it to tip4popls.itp and replaced 

[ atoms ]
; id	at type	res nr 	residu name	at name		cg nr	charge
1	OP113	1	SOL		 OW		1	0
2	OP114	1	SOL		HW1		1	0.52
3	OP114	1	SOL		HW2		1	0.52
4	OP115	1	SOL		 MW		1      -1.04

with 

[ atoms ]
; id	at type	res nr 	residu name	at name		cg nr	charge
1       opls_113   1      SOL            OW             1       0
2       opls_114   1      SOL           HW1             1       0.52
3       opls_114   1      SOL           HW2             1       0.52
4       opls_115   1      SOL            MW             1      -1.04

Genbox works fine with tip4p.gro. 

-Graham