espressopp.interaction.ConstrainCOM

This class is for calculating forces acting on constrained center of mass of subchains [Zhang_2014].

Subchains are defined as a tuple list.

\[U = k_{com} \left(\vec{r_{com}} - \vec{R_{com}}\right)^2,\]

where \(\vec{r_{com}}\) stands for the center of mass of subchain and \(\vec{R_{com}}\) stands for the desired center of mass of subchain.

This class implies 2 conditions on a tuple list defining subchains:

  1. The length of all tuples must be the same.

  2. int(key particle id / The length of a tuple) must not be redundantly, where key particle id is the smallest particle id in a tuple.

[Zhang_2014]

G. Zhang, L. A. Moreira, T. Stuehn, K. Ch. Daoulas, and K. Kremer, Equilibration of high molecular weight polymer melts: A hierarchical strategy, Macro Lett., 2014, 3, 198

espressopp.interaction.ConstrainCOM(k_com)
Parameters:

k_com (real) – (default: 100.)

espressopp.interaction.FixedLocalTupleListConstrainCOM(system, tuplelist, potential)
Parameters:

  • system

  • tuplelist

  • potential

espressopp.interaction.FixedLocalTupleListConstrainCOM.getPotential()
Return type:

espressopp.interaction.FixedLocalTupleListConstrainCOM.setCom(particlelist)
Parameters:

particlelist