MD-SCF

MDSCF force

Description:

Using hybrid particle-field technique to accelerate CGMD simulations (G. Milano and T. Kawakatsu, J. Chem. Phys. 130, 214106, 2009). This method could largely speed up some slowly evolving processes in CGMD simulations, such as microphase separation and self-assembly of polymeric systems.

class MDSCFForce(AllInfo all_info, int nx, int ny, int nz, float comp)

Constructor of an object of MD-SCF force.

Parameters:

  • all_info (AllInfo) – System information.

  • nx (int) – Number of grid in x direction.

  • ny (int) – Number of grid in y direction.

  • nz (int) – Number of grid in z direction.

  • comp (float) – Compressibility.

setPeriodScf(int idl2_step, int idl_step)

sets the periods of computing density field and updating density field.

setParams(string type1, string type2, float chi)

specifies the MD-SCF interaction parameters by pair types with type1, type2, chi parameter.

setNewVersion(bool switch)

switches the function of newly developed method of implementation.

Example:

scf = gala.MDSCFForce(all_info, 22, 22, 22, 0.100)
scf.setParams('N', 'N',0.000)
scf.setParams('N', 'P',-1.500)
scf.setParams('P', 'P',0.000)
scf.setPeriodScf(1,300)
scf.setNewVersion(True)
# switches to newly developed version.
app.add(scf)
# adds this object to the application.

MDSCF electrostatic force

class PFMEForce(AllInfo all_info, int nx, int ny, int nz, float kappa, float epsilonr)

Constructor of an object to calculate electrostatic forces in MD-SCF framework.

Parameters:

  • all_info (AllInfo) – System information.

  • nx (int) – Number of grid in x direction.

  • ny (int) – Number of grid in y direction.

  • nz (int) – Number of grid in z direction.

  • kappa (float) – kappa = 1/(sqrt(2)sigma) where sigma is the standard deviation of the Gaussian charge distribution.

  • epsilonr (float) – Relative dielectric constant.

setPeriodPFME(int idl2_step, int idl_step)

sets the periods of computing density field and updating density field.

setNewVersion(bool switch)

switches the function of newly developed method of implementation.

Example:

pfme = gala.PFMEForce(all_info,    32,   32,   36,  2.45,  epsilonr)#(mx,my,mz, kappa, epsilonr)
pfme.setPeriodPFME(1,  100)#(idl2_step, idl_step)
app.add(pfme)