ESPResSo
Extensible Simulation Package for Research on Soft Matter Systems
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lj.hpp
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1/*
2 * Copyright (C) 2010-2022 The ESPResSo project
3 * Copyright (C) 2002,2003,2004,2005,2006,2007,2008,2009,2010
4 * Max-Planck-Institute for Polymer Research, Theory Group
5 *
6 * This file is part of ESPResSo.
7 *
8 * ESPResSo is free software: you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation, either version 3 of the License, or
11 * (at your option) any later version.
12 *
13 * ESPResSo is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program. If not, see <http://www.gnu.org/licenses/>.
20 */
21#ifndef CORE_NB_IA_LJ_HPP
22#define CORE_NB_IA_LJ_HPP
23
24#include "config/config.hpp"
25
26#ifdef LENNARD_JONES
27
28/** \file
29 * Routines to calculate the Lennard-Jones potential between particle pairs.
30 *
31 * Implementation in \ref lj.cpp.
32 */
33
35
36#include <utils/Vector.hpp>
38#include <utils/math/sqr.hpp>
39
40/** Calculate Lennard-Jones force factor */
41inline double lj_pair_force_factor(IA_parameters const &ia_params,
42 double dist) {
43 if (dist < ia_params.lj.max_cutoff() and dist > ia_params.lj.min_cutoff()) {
44 auto const r_off = dist - ia_params.lj.offset;
45 auto const frac6 = Utils::int_pow<6>(ia_params.lj.sig / r_off);
46 return 48.0 * ia_params.lj.eps * frac6 * (frac6 - 0.5) / (r_off * dist);
47 }
48 return 0.0;
49}
50
51/** Calculate Lennard-Jones energy */
52inline double lj_pair_energy(IA_parameters const &ia_params, double dist) {
53 if (dist < ia_params.lj.max_cutoff() and dist > ia_params.lj.min_cutoff()) {
54 auto const r_off = dist - ia_params.lj.offset;
55 auto const frac6 = Utils::int_pow<6>(ia_params.lj.sig / r_off);
56 return 4.0 * ia_params.lj.eps *
57 (Utils::sqr(frac6) - frac6 + ia_params.lj.shift);
58 }
59 return 0.0;
60}
61
62#endif /* ifdef LENNARD_JONES */
63#endif
Vector implementation and trait types for boost qvm interoperability.
This file contains the defaults for ESPResSo.
double lj_pair_force_factor(IA_parameters const &ia_params, double dist)
Calculate Lennard-Jones force factor.
Definition lj.hpp:41
double lj_pair_energy(IA_parameters const &ia_params, double dist)
Calculate Lennard-Jones energy.
Definition lj.hpp:52
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.