# Difference between revisions of "SPC/E model of water"

The SPC/E (extended simple point charge model) [1] [2] is a slight reparameterisation of the SPC model of water, with a modified value for $q_{\mathrm{O}}$. The molecule is modelled as a rigid isosceles triangle, having charges situated on each of the three atoms. Apart from Coulombic interactions, the molecules interact via long-range Lennard-Jones sites, situated on the oxygen atoms. The parameters are as follows:

 parameter value $\sigma$ $3.166$ Å $\epsilon$ $0.650$ kJ mol-1 $r_\mathrm{OH}$ $1.000$ Å $\angle_\mathrm{HOH}$ $109.47^{\circ}$ $q_{\mathrm{O}}$ $-0.8476 e$ $q_{\mathrm{H}}$ $q_{\mathrm{O}}/2$ (charge neutrality)

The SPC/E model has a dipole moment of 2.351 D. (Ref. 1 Table I).

## Surface tension

The surface tension has been studied for the SPC/E model by Vega and Miguel [3]

## Phase diagram

### Plastic crystal phases

Recent simulations have demonstrated the existence of plastic crystal phases for the SPC/E model. [4]

## Shear viscosity

The shear viscosity for the SPC/E model is 0.729 mPa.s at 298 K and 1 bar [5] (experimental value 0.896 mPa.s [6]).