[gmx-users] tip5p water model

[Yuguang Mu]

Dear all,
I have used TIP5P water model (published in JCP 112, p8910 (2000)),
in gromacs-3.1.4.
Here is my results (216 water)  (1 ns average after 5ns equilibration) (300K)

density  (g/cm^3)        9.8066 
-E         (kcal/mol)       7.619  


while the published value are (25 oC)

density  (g/cm^3)        9.999 
-E         (kcal/mol)       9.87

Of couse they use Monte Carlo statistical calculations.
The question is that I use exactly the same parameters as the published one,
but I cannot get the exact results. Specially the energy is quite low !

What's the origin ?

-------------- next part --------------
[ moleculetype ]
; molname	nrexcl
SOL            	1

[ atoms ]
; id	at type	res nr 	residu name	at name		cg nr	charge
1      opls_108	1	SOL 		 OW		1	0
2      opls_109 1	SOL 		HW1		1	0.241
3      opls_109	1	SOL 		HW2		1	0.241
4      opls_110	1	SOL 		MW1		1      -0.241
5      opls_110 1       SOL             MW2             1      -0.241
 
[ settles ]
; i	funct	doh	dhh
1	1	0.09572	0.15139

; The position of the dummy is computed as follows:
;
;		O
;  	      
;	    	D
;	  
;	H		H
;
; const = distance (OD) / [ cos (angle(DOH)) 	* distance (OH) ]
;	  0.015 nm	/ [ cos (52.26 deg)	* 0.09572 nm	]

; Dummy pos x4 = x1 + a*(x2-x1) + b*(x3-x1) + c*((x2-x1) x (x3-x1))

[ dummies3 ]
; Dummy from			funct	a		b                    c
4	1	2	3	4      -0.344908        -0.344908          -6.44381

[ dummies3 ]
; Dummy from                    funct   a               b                    c
5       1       2       3       4      -0.344908        -0.344908           6.44381

[ exclusions ]
1	2	3	4       5
2	1	3	4       5
3	1	2	4       5 
4	1	2	3       5
5       1       2       3       4