Files
lammps/lib/colvars/colvarcomp_alchlambda.cpp
2024-08-06 01:07:43 +02:00

101 lines
2.4 KiB
C++

// -*- c++ -*-
// This file is part of the Collective Variables module (Colvars).
// The original version of Colvars and its updates are located at:
// https://github.com/Colvars/colvars
// Please update all Colvars source files before making any changes.
// If you wish to distribute your changes, please submit them to the
// Colvars repository at GitHub.
#include <algorithm>
#include "colvarmodule.h"
#include "colvarvalue.h"
#include "colvar.h"
#include "colvarcomp.h"
colvar::alch_lambda::alch_lambda()
{
set_function_type("alchLambda");
disable(f_cvc_explicit_gradient);
disable(f_cvc_gradient);
x.type(colvarvalue::type_scalar);
// Query initial value from back-end
cvm::proxy->get_alch_lambda(&x.real_value);
}
void colvar::alch_lambda::calc_value()
{
// Special workflow:
// at the beginning of the timestep we get a force instead of calculating the value
cvm::proxy->get_dE_dlambda(&ft.real_value);
ft.real_value *= -1.0; // Energy derivative to force
// Include any force due to bias on Flambda
ft.real_value += cvm::proxy->indirect_lambda_biasing_force;
cvm::proxy->indirect_lambda_biasing_force = 0.0;
}
void colvar::alch_lambda::calc_gradients()
{
}
void colvar::alch_lambda::apply_force(colvarvalue const & /* force */)
{
// new value will be cached and sent at end of timestep
cvm::proxy->set_alch_lambda(x.real_value);
}
colvar::alch_Flambda::alch_Flambda()
{
set_function_type("alch_Flambda");
disable(f_cvc_explicit_gradient);
disable(f_cvc_gradient);
x.type(colvarvalue::type_scalar);
}
void colvar::alch_Flambda::calc_value()
{
// Special workflow:
// at the beginning of the timestep we get a force instead of calculating the value
// Query initial value from back-end
cvm::proxy->get_dE_dlambda(&x.real_value);
x.real_value *= -1.0; // Energy derivative to force
}
void colvar::alch_Flambda::calc_gradients()
{
}
void colvar::alch_Flambda::apply_force(colvarvalue const &force)
{
// Convert force on Flambda to force on dE/dlambda
cvm::real f = -1.0 * force.real_value;
// Send scalar force to back-end, which will distribute it onto atoms
cvm::proxy->apply_force_dE_dlambda(&f);
// Propagate force on Flambda to lambda internally
cvm::real d2E_dlambda2;
cvm::proxy->get_d2E_dlambda2(&d2E_dlambda2);
// This accumulates a force, it needs to be zeroed when taken into account by lambda
cvm::proxy->indirect_lambda_biasing_force += d2E_dlambda2 * f;
}