[610c11] | 1 | /*
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| 2 | * Project: MoleCuilder
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| 3 | * Description: creates and alters molecular systems
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| 4 | * Copyright (C) 2012 University of Bonn. All rights reserved.
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| 5 | * Please see the COPYING file or "Copyright notice" in builder.cpp for details.
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| 6 | *
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| 7 | *
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| 8 | * This file is part of MoleCuilder.
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| 9 | *
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| 10 | * MoleCuilder is free software: you can redistribute it and/or modify
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| 11 | * it under the terms of the GNU General Public License as published by
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| 12 | * the Free Software Foundation, either version 2 of the License, or
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| 13 | * (at your option) any later version.
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| 14 | *
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| 15 | * MoleCuilder is distributed in the hope that it will be useful,
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| 16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 18 | * GNU General Public License for more details.
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| 19 | *
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| 20 | * You should have received a copy of the GNU General Public License
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| 21 | * along with MoleCuilder. If not, see <http://www.gnu.org/licenses/>.
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| 22 | */
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| 23 |
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| 24 | /*
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| 25 | * ManyBodyPotential_Tersoff.cpp
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| 26 | *
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| 27 | * Created on: Sep 26, 2012
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| 28 | * Author: heber
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| 29 | */
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| 30 |
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| 31 |
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| 32 | // include config.h
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| 33 | #ifdef HAVE_CONFIG_H
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| 34 | #include <config.h>
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| 35 | #endif
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| 36 |
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| 37 | #include "CodePatterns/MemDebug.hpp"
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| 38 |
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| 39 | #include "ManyBodyPotential_Tersoff.hpp"
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| 40 |
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| 41 | #include <boost/bind.hpp>
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| 42 | #include <cmath>
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| 43 |
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| 44 | #include "CodePatterns/Assert.hpp"
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| 45 |
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| 46 | #include "Potentials/helpers.hpp"
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| 47 |
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[4f82f8] | 48 | ManyBodyPotential_Tersoff::results_t
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[610c11] | 49 | ManyBodyPotential_Tersoff::operator()(
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| 50 | const arguments_t &arguments
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| 51 | ) const
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| 52 | {
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| 53 | const double &distance = arguments[0].distance;
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| 54 | const double cutoff = function_cutoff(distance);
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| 55 | const double result = (cutoff == 0.) ? 0. : cutoff * (
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| 56 | function_prefactor(
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| 57 | manybodyparameter_alpha,
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| 58 | boost::bind(&ManyBodyPotential_Tersoff::function_eta,
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| 59 | boost::cref(*this),
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| 60 | boost::cref(arguments[0])))
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| 61 | * function_smoother(
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| 62 | distance,
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| 63 | manybodyparameter_A,
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| 64 | manybodyparameter_lambda1)
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| 65 | +
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| 66 | function_prefactor(
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| 67 | manybodyparameter_beta,
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| 68 | boost::bind(&ManyBodyPotential_Tersoff::function_zeta,
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| 69 | boost::cref(*this),
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| 70 | boost::cref(arguments[0])))
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| 71 | * function_smoother(
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| 72 | distance,
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| 73 | -manybodyparameter_B,
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| 74 | manybodyparameter_lambda2)
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| 75 | );
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[4f82f8] | 76 | return std::vector<result_t>(1, result);
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[610c11] | 77 | }
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| 78 |
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[4f82f8] | 79 | ManyBodyPotential_Tersoff::result_t
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[610c11] | 80 | ManyBodyPotential_Tersoff::function_cutoff(
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| 81 | const double &distance
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| 82 | ) const
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| 83 | {
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| 84 | const double offset = (distance - cutoff_offset);
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| 85 | if (offset < - cutoff_halfwidth)
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| 86 | return 1.;
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| 87 | else if (offset > cutoff_halfwidth)
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| 88 | return 0.;
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| 89 | else {
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| 90 | return (0.5 - 0.5 * sin( .5 * M_PI * offset/cutoff_halfwidth));
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| 91 | }
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| 92 | }
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| 93 |
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[4f82f8] | 94 | ManyBodyPotential_Tersoff::result_t
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[610c11] | 95 | ManyBodyPotential_Tersoff::function_prefactor(
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| 96 | const double &alpha,
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| 97 | boost::function<result_t()> etafunction
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| 98 | ) const
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| 99 | {
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| 100 | return pow(
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| 101 | (1. + Helpers::pow(alpha * etafunction(), manybodyparameter_n)),
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| 102 | -1./(2.*manybodyparameter_n));
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| 103 | }
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| 104 |
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[4f82f8] | 105 | ManyBodyPotential_Tersoff::result_t
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[610c11] | 106 | ManyBodyPotential_Tersoff::function_eta(
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| 107 | const argument_t &r_ij
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| 108 | ) const
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| 109 | {
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| 110 | result_t result = 0.;
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| 111 |
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| 112 | // get all triples within the cutoff
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| 113 | std::vector<arguments_t> triples = triplefunction(r_ij, cutoff_offset+cutoff_halfwidth);
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| 114 | for (std::vector<arguments_t>::const_iterator iter = triples.begin();
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| 115 | iter != triples.end(); ++iter) {
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| 116 | ASSERT( iter->size() == 2,
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| 117 | "ManyBodyPotential_Tersoff::function_zeta() - the triples result must contain of exactly two distances.");
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| 118 | const argument_t &r_ik = (*iter)[0];
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| 119 | result += function_cutoff(r_ik.distance)
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| 120 | * exp( Helpers::pow(manybodyparameter_lambda3 * (r_ij.distance - r_ik.distance) ,3));
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| 121 | }
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| 122 |
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| 123 | return result;
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| 124 | }
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| 125 |
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[4f82f8] | 126 | ManyBodyPotential_Tersoff::result_t
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[610c11] | 127 | ManyBodyPotential_Tersoff::function_zeta(
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| 128 | const argument_t &r_ij
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| 129 | ) const
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| 130 | {
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| 131 | result_t result = 0.;
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| 132 |
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| 133 | // get all triples within the cutoff
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| 134 | std::vector<arguments_t> triples = triplefunction(r_ij, cutoff_offset+cutoff_halfwidth);
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| 135 | for (std::vector<arguments_t>::const_iterator iter = triples.begin();
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| 136 | iter != triples.end(); ++iter) {
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| 137 | ASSERT( iter->size() == 2,
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| 138 | "ManyBodyPotential_Tersoff::function_zeta() - the triples result must contain exactly two distances.");
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| 139 | const argument_t &r_ik = (*iter)[0];
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| 140 | const argument_t &r_jk = (*iter)[1];
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| 141 | result +=
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| 142 | function_cutoff(r_ik.distance)
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| 143 | * function_angle(r_ij.distance, r_ik.distance, r_jk.distance)
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| 144 | * exp( Helpers::pow(manybodyparameter_lambda3 * (r_ij.distance - r_ik.distance) ,3));
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| 145 | }
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| 146 |
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| 147 | return result;
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| 148 | }
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| 149 |
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[4f82f8] | 150 | ManyBodyPotential_Tersoff::result_t
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[610c11] | 151 | ManyBodyPotential_Tersoff::function_angle(
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| 152 | const double &r_ij,
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| 153 | const double &r_ik,
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| 154 | const double &r_jk
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| 155 | ) const
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| 156 | {
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| 157 | const double angle = Helpers::pow(r_ij,2) + Helpers::pow(r_ik,2) - Helpers::pow(r_jk,2);
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| 158 | const double divisor = r_ij * r_ik;
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| 159 | const double result =
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| 160 | 1.
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| 161 | + (Helpers::pow(manybodyparameter_c, 2)/Helpers::pow(manybodyparameter_d, 2))
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| 162 | - Helpers::pow(manybodyparameter_c, 2)/(Helpers::pow(manybodyparameter_d, 2) +
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| 163 | Helpers::pow(manybodyparameter_h - cos(angle/divisor),2));
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| 164 | return result;
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| 165 | }
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