ESPResSo
Extensible Simulation Package for Research on Soft Matter Systems
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wca.hpp
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1/*
2 * Copyright (C) 2018-2022 The ESPResSo project
3 *
4 * This file is part of ESPResSo.
5 *
6 * ESPResSo is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
10 *
11 * ESPResSo is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 */
19#ifndef WCA_HPP
20#define WCA_HPP
21/** \file
22 * Routines to calculate the Weeks-Chandler-Andersen potential between
23 * particle pairs.
24 *
25 * Implementation in \ref wca.cpp.
26 */
27
28#include "config/config.hpp"
29
30#ifdef WCA
31
33
34#include <utils/Vector.hpp>
36#include <utils/math/sqr.hpp>
37
38/** Calculate WCA force factor */
39inline double wca_pair_force_factor(IA_parameters const &ia_params,
40 double dist) {
41 if (dist < ia_params.wca.cut) {
42 auto const frac6 = Utils::int_pow<6>(ia_params.wca.sig / dist);
43 return 48.0 * ia_params.wca.eps * frac6 * (frac6 - 0.5) / (dist * dist);
44 }
45 return 0.0;
46}
47
48/** Calculate WCA energy */
49inline double wca_pair_energy(IA_parameters const &ia_params, double dist) {
50 if (dist < ia_params.wca.cut) {
51 auto const frac6 = Utils::int_pow<6>(ia_params.wca.sig / dist);
52 return 4.0 * ia_params.wca.eps * (Utils::sqr(frac6) - frac6 + .25);
53 }
54 return 0.0;
55}
56
57#endif /* ifdef WCA */
58#endif
Vector implementation and trait types for boost qvm interoperability.
This file contains the defaults for ESPResSo.
DEVICE_QUALIFIER constexpr T sqr(T x)
Calculates the SQuaRe of x.
Definition sqr.hpp:28
Various procedures concerning interactions between particles.
Parameters for non-bonded interactions.
double wca_pair_energy(IA_parameters const &ia_params, double dist)
Calculate WCA energy.
Definition wca.hpp:49
double wca_pair_force_factor(IA_parameters const &ia_params, double dist)
Calculate WCA force factor.
Definition wca.hpp:39