|
|
| (9 intermediate revisions by 5 users not shown) |
| Line 1: |
Line 1: |
| This is a common method to obtain the [[pressure]] from a general simulation (it is best suited for [[molecular dynamics]] since forces are evaluated in this case). For central interactions, one has:
| | #REDIRECT[[Pressure#Virial pressure]] |
| | |
| :<math> p = \frac{ k_B T N}{V} - \frac{ 1 }{ d V } \overline{ \sum_{i<j} {\mathbf f}_{ij} {\mathbf r}_{ij} }, </math>
| |
| | |
| where one can recognize an ideal term and another one due to the [[virial]]. The underline is an average, which would be a time average in molecular dynamics, or ensamble average in [[Monte Carlo]]; <math>d</math> is the dimension of the system (3 in actual world). <math> {\mathbf f}_{ij} </math> is the force '''on''' particle <math>i</math> exerted '''by''' particle <math>j</math>, and <math>{\mathbf r}_{ij}</math> is the vector going '''from''' <math>i</math> '''to''' <math>j</math>: <math>{\mathbf r}_{ij} = {\mathbf r}_j - {\mathbf r}_i</math>.
| |