# simulations at constant pressure-volume and constant volume-temperature

I have read some papers where the authors perform simulations at constant pressure and constant volumen or sometimes constant volume constant temperature. My question is when is it better to use one or the other? For which systems it would be ok to perform constant p-t and for which would be better constant v-t?

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I don't see how anyone could answer this question without knowing about what kinds of simulations you are thinking about doing, what the purpose of the simulation is and even what kinds of materials you would be simulating - for example, is it a solid, a liquid or a gas. Please edit and expand your question by including more of this kind of information. –  FrankH Oct 11 '11 at 1:17
eg "at constant pressure and constant volume is not very interesting. I guess You remember wrongly. –  Georg Oct 11 '11 at 8:46
I'm talking about molecular dynamics simulations of biomolecules + water + ions. –  armando Oct 11 '11 at 18:03