View source for Gamma p

<code>gamma_p</code> sets a "bulk modulus"-like quantity that determines, together with <code>[[tau_p]]</code>, the strength of the coupling to the [[barostat]]. In '''TurboGAP''', <code>gamma_p</code> is given in units of the inverse compressibility of water, <math>1 / (4.5 \times 10^5 \text{ bar}^{-1})</math>. While this may seem complicated, it provides a convenient and intuitive way to select <code>gamma_p</code> in terms of how incompressible (or "rigid") one expects the system under study to be, compared to water. For instance, for typical solids <math>\gamma_P \gg 1</math> whereas for gasses <math>\gamma_P \ll 1</math>. For most organic and molecular liquids <math>\gamma_P \approx 1</math> should be a suitable choice. A simple way to select the optimal <code>[[gamma_p]]</code> is to divide the bulk modulus of the system under study by the bulk modulus of water.

=== Summary ===

{| class="wikitable"
|+ Summary for <code>gamma_p</code> keyword
! style="text-align:left;"| Required/optional
! style="text-align:left;"| Type
! style="text-align:left;"| Accepted values
! style="text-align:left;"| Default
! style="text-align:left;"| See also
|-
| Optional
| Real
| Any positive real
| 1.
| <code>[[barostat]]</code>, <code>[[p_end]]</code>, <code>[[tau_p]]</code>, <code>[[gamma_p]]</code>
|}

=== Example ===

 [[barostat]] = "berendsen"
 [[barostat_sym]] = "iso"
 [[p_beg]] = 10. # in bar
 [[p_end]] = 10. # in bar
 [[tau_p]] = 100. # in fs
 [[gamma_p]] = 10. # in units of the inverse compressibility of water