Editing Constant-pressure Monte Carlo

In '''constant-pressure Monte Carlo''' a trial change in the volume becomes one of the [[Monte Carlo]] moves.
The [[weighting function]], ''w'', is given by (Ref 1 Eq. 2)

:<math>w \simeq c \frac{V^N}{N!} \exp \left[ -\beta ( U(q^N)) +pV \right]</math>

for a change in volume, <math>\Delta V</math>, one has

:<math>r = \frac{w_{\rm new}}{w_{\rm old}} = \exp \left[ -\beta \left( \Delta U + p\Delta V - Nk_BT \ln \frac{V+\Delta V}{V}\right)\right]</math>

If <math>r \ge 1</math> then the move is accepted, and if <math>0 < r < 1</math> then ''r'' is compared with a random number
<math>0 < x < 1</math>.  If <math>x \le r</math> then the move is accepted.

==References==
#[http://dx.doi.org/10.1080/00268978400101951 R. Eppenga and D. Frenkel "Monte Carlo study of the isotropic and nematic phases of infinitely thin hard platelets", Molecular Physics '''52''' pp. 1303-1334 (1984)]
[[category: Monte Carlo]]