espressopp/espressopp

#  Copyright (C) 2012,2013,2016
#      Max Planck Institute for Polymer Research
#  Copyright (C) 2008,2009,2010,2011
#      Max-Planck-Institute for Polymer Research & Fraunhofer SCAI
#
#  This file is part of ESPResSo++.
#
#  ESPResSo++ is free software: you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation, either version 3 of the License, or
#  (at your option) any later version.
#
#  ESPResSo++ is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program.  If not, see <http://www.gnu.org/licenses/>.


import espressopp
from espressopp import Real3D

def warmup(system, integrator, number = 80):
    """
    Warm up for a system with a density of 0.85.

    The method needs the following parameters:

    * system, integrator
      ESPResSo system which schoul be warmed up and the correspondig integrator e.g.:

      >>> system, integrator = espressopp.standard_system.LennardJones(100,(10,10,10))

    * number
      number of steps of the warm up

      for a system with a density of 0.85, if it explodes try a higher number

    """
    print("starting warmup")

    org_dt = integrator.dt
    pot = system.getInteraction(0).clonePotential(0,0)
    final_sigma = pot.sigma
    final_epsilon = pot.epsilon
    N = 50

    integrator.dt = 0.0001
    force_capping = espressopp.integrator.CapForce(system, 0.0)
    integrator.addExtension(force_capping)

    for k in range(11,number):
        force_capping.setAbsCapForce(1000000.0/number*k)
        pot.sigma = final_sigma/number*k
        pot.epsilon = final_epsilon/number*k
        system.getInteraction(0).setPotential(0,0,pot)
        espressopp.tools.analyse.info(system, integrator)
        integrator.run(N)

    integrator.dt = org_dt
    pot.sigma = final_sigma
    pot.epsilon = final_epsilon
    force_capping.disconnect()

    for k in range(11):
        integrator.run(70)
        espressopp.tools.analyse.info(system, integrator)

    integrator.step = 0

    print("warmup finished")