NPT ensemble

Overview

Andersen barostat

NPT

NPT for rigid body

NPTRigid

Andersen barostat

Reference: H. C. Andersen, J. Chem. Phys., 1980, 72(4), 2384-2393.

class NPT(all_info, group, comp_info_group, comp_info_all, T, P, tauT, tauP)

The constructor of a NPT thermostat object for a group of particles.

Parameters:

  • all_info (AllInfo) – The system information.

  • group (ParticleSet) – The group of particles.

  • comp_info_group (ComputeInfo) – The calculation of collective information of group particles.

  • comp_info_all (ComputeInfo) – The calculation of collective information of all particles.

  • T (float) – The temperature.

  • P (float) – The pressure.

  • tauT (float) – The thermostat coupling.

  • tauP (float) – The barostat coupling.

setP(float P)

specifies the pressure with a constant value.

setT(float T)

specifies the temperature with a constant value.

setT(Variant vT)

specifies the temperature with a varying value by time step.

Example:

npt =gala.NPT(all_info, group, comp_info, comp_info, 1.0, 0.2, 0.5, 0.1)
app.add(npt)

NPT for rigid body

class NPTRigid(all_info, group, comp_info_group, comp_info_all, T, P, tauT, tauP)

The constructor of a NPT thermostat object for rigid bodies.

Parameters:

  • all_info (AllInfo) – The system information.

  • group (ParticleSet) – The group of particles.

  • comp_info_group (ComputeInfo) – The calculation of collective information of group particles.

  • comp_info_all (ComputeInfo) – The calculation of collective information of all particles.

  • T (float) – The temperature.

  • P (float) – The pressure.

  • tauT (float) – The thermostat coupling.

  • tauP (float) – The barostat coupling.

setT(float T)

specifies the temperature with a fixed value.

setT(Variant vT)

specifies the temperature with a varying value by time step.

setP(float P)

specifies the pressure with a fixed value.

Example:

group = gala.ParticleSet(all_info,'all')
comp_info = gala.ComputeInfo(all_info, group)

bgroup = gala.ParticleSet(all_info, 'body')
comp_info_b = gala.ComputeInfo(all_info, bgroup)

rigidnpt = gala.NPTRigid(all_info, bgroup, comp_info_b, comp_info, 1.0, 0.1, 1.0, 1.0)
app.add(rigidnpt)

Martyna-Tobias-Klein barostat

Reference: G. J. Martyna, D. J. Tobias, and M. L. Klein, J. Chem. Phys., 1994, 101(5), 4177-4189.

class NPTMTK(all_info, group, comp_info_group, comp_info_all, T, P, tauT, tauP)

The constructor of a NPTMTK thermostat object for a group of particles.

Parameters:

  • all_info (AllInfo) – The system information.

  • group (ParticleSet) – The group of particles.

  • comp_info_group (ComputeInfo) – The calculation of collective information of group particles.

  • comp_info_all (ComputeInfo) – The calculation of collective information of all particles.

  • T (float) – The temperature.

  • P (float) – The pressure.

  • tauT (float) – The thermostat coupling.

  • tauP (float) – The barostat coupling.

setT(float T)

specifies the temperature with a fixed value.

setT(Variant vT)

specifies the temperature with a varying value by time step.

setSemiisotropic(float pressxy, float pressz)

specifies the pressure with fixed values for XY and Z directions, respectively.

setSemiisotropic(float pressxy, Variant vpressz)

specifies the pressure with a fixed value for XY direction and a varying value for Z direction, respectively.

setAnisotropic(float pressx, float pressy, float pressz)

specifies the pressure with fixed values for X, Y and Z directions, respectively.

Example:

group = gala.ParticleSet(all_info,'all')
comp_info = gala.ComputeInfo(all_info, group)

npt = gala.NPTMTK(all_info, group, comp_info, comp_info, 1.0, 0.1, 0.5, 1.0)
npt.setSemiisotropic(0.1, 0.1)
app.add(npt)

Martyna-Tobias-Klein barostat for rigid body

Reference: G. J. Martyna, D. J. Tobias, and M. L. Klein, J. Chem. Phys., 1994, 101(5), 4177-4189.

class NPTMTKRigid(all_info, group, comp_info_group, comp_info_all, T, P, tauT, tauP)

The constructor of a NPTMTK thermostat object for rigid bodies.

Parameters:

  • all_info (AllInfo) – The system information.

  • group (ParticleSet) – The group of particles.

  • comp_info_group (ComputeInfo) – The calculation of collective information of group particles.

  • comp_info_all (ComputeInfo) – The calculation of collective information of all particles.

  • T (float) – The temperature.

  • P (float) – The pressure.

  • tauT (float) – The thermostat coupling.

  • tauP (float) – The barostat coupling.

setT(float T)

specifies the temperature with a fixed value.

setT(Variant vT)

specifies the temperature with a varying value by time step.

setSemiisotropic(float pressxy, float pressz)

specifies the pressure with fixed values for XY and Z directions, respectively.

setSemiisotropic(float pressxy, Variant vpressz)

specifies the pressure with a fixed value for XY direction and a varying value for Z direction, respectively.

setAnisotropic(float pressx, float pressy, float pressz)

specifies the pressure with fixed values for X, Y and Z directions, respectively.

Example:

group = gala.ParticleSet(all_info,'all')
comp_info = gala.ComputeInfo(all_info, group)

groupb = gala.ParticleSet(all_info, 'body')
comp_info_b = gala.ComputeInfo(all_info, groupb)

npt = gala.NPTMTKRigid(all_info, groupb, comp_info_b, comp_info, 1.0, 0.1, 0.5, 1.0)
npt.setSemiisotropic(0.1, 0.1)
app.add(npt)