GROMACS topology file for the TIP4P/Ice model

The following is a topology file for the TIP4P/Ice model of water for use in the GROMACS computer simulation package.

The best way to use this file is to click on the edit tab at the top of this page, and then cut and paste the relevant section in the edit window to the file topol.top

```

[ defaults ]

nbfunc comb-rule gen-pairs fudgeLJ fudgeQQ

 1             2               no              1.0     1.0

[atomtypes]

name mass charge ptype sigma epsilon

IW 0 0.000 D 0.0 0.0 OWT4 15.99940 0.000 A 0.31668 0.88211 HW 1.00800 0.000 A 0.00000E+00 0.00000E+00

[moleculetype]

name nrexcl

water 1

[atoms]

nr type resnr residu atom cgnr charge

1 OWT4 1 water OW1 1 0 15.994 2 HW 1 water HW2 1 0.5897 1.008 3 HW 1 water HW3 1 0.5897 1.008 4 IW 1 water MW4 1 -1.1794 0.0

[constraints]

i j funct doh dhh

1 2 1 0.09572 1 3 1 0.09572 2 3 1 0.15139

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

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)

[dummies3]

Dummy from funct a b

4 1 2 3 1 0.13458 0.13458

[system] water TIP4P/Ice

[molecules] water 1

```