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root/group/trunk/OOPSE-2.0/src/integrators/Velocitizer.cpp
Revision: 2256
Committed: Tue May 31 22:31:54 2005 UTC (19 years ago) by chuckv
File size: 7786 byte(s)
Log Message:
Changes to remove angular momentum.

File Contents

# Content
1 /*
2 * Copyright (c) 2005 The University of Notre Dame. All Rights Reserved.
3 *
4 * The University of Notre Dame grants you ("Licensee") a
5 * non-exclusive, royalty free, license to use, modify and
6 * redistribute this software in source and binary code form, provided
7 * that the following conditions are met:
8 *
9 * 1. Acknowledgement of the program authors must be made in any
10 * publication of scientific results based in part on use of the
11 * program. An acceptable form of acknowledgement is citation of
12 * the article in which the program was described (Matthew
13 * A. Meineke, Charles F. Vardeman II, Teng Lin, Christopher
14 * J. Fennell and J. Daniel Gezelter, "OOPSE: An Object-Oriented
15 * Parallel Simulation Engine for Molecular Dynamics,"
16 * J. Comput. Chem. 26, pp. 252-271 (2005))
17 *
18 * 2. Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 *
21 * 3. Redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the
24 * distribution.
25 *
26 * This software is provided "AS IS," without a warranty of any
27 * kind. All express or implied conditions, representations and
28 * warranties, including any implied warranty of merchantability,
29 * fitness for a particular purpose or non-infringement, are hereby
30 * excluded. The University of Notre Dame and its licensors shall not
31 * be liable for any damages suffered by licensee as a result of
32 * using, modifying or distributing the software or its
33 * derivatives. In no event will the University of Notre Dame or its
34 * licensors be liable for any lost revenue, profit or data, or for
35 * direct, indirect, special, consequential, incidental or punitive
36 * damages, however caused and regardless of the theory of liability,
37 * arising out of the use of or inability to use software, even if the
38 * University of Notre Dame has been advised of the possibility of
39 * such damages.
40 */
41
42 #include "integrators/Velocitizer.hpp"
43 #include "math/SquareMatrix3.hpp"
44 #include "primitives/Molecule.hpp"
45 #include "primitives/StuntDouble.hpp"
46
47 #ifndef IS_MPI
48 #include "math/SeqRandNumGen.hpp"
49 #else
50 #include "math/ParallelRandNumGen.hpp"
51 #endif
52
53 /* Remove me after testing*/
54 #include <cstdio>
55 #include <iostream>
56 /*End remove me*/
57
58 namespace oopse {
59
60 Velocitizer::Velocitizer(SimInfo* info) : info_(info) {
61
62 int seedValue;
63 Globals * simParams = info->getSimParams();
64
65 #ifndef IS_MPI
66 if (simParams->haveSeed()) {
67 seedValue = simParams->getSeed();
68 randNumGen_ = new SeqRandNumGen(seedValue);
69 }else {
70 randNumGen_ = new SeqRandNumGen();
71 }
72 #else
73 if (simParams->haveSeed()) {
74 seedValue = simParams->getSeed();
75 randNumGen_ = new ParallelRandNumGen(seedValue);
76 }else {
77 randNumGen_ = new ParallelRandNumGen();
78 }
79 #endif
80 }
81
82 Velocitizer::~Velocitizer() {
83 delete randNumGen_;
84 }
85
86 void Velocitizer::velocitize(double temperature) {
87 Vector3d aVel;
88 Vector3d aJ;
89 Mat3x3d I;
90 int l;
91 int m;
92 int n;
93 Vector3d vdrift;
94 double vbar;
95 /**@todo refactory kb */
96 const double kb = 8.31451e-7; // kb in amu, angstroms, fs, etc.
97 double av2;
98 double kebar;
99
100 Globals * simParams = info_->getSimParams();
101
102 SimInfo::MoleculeIterator i;
103 Molecule::IntegrableObjectIterator j;
104 Molecule * mol;
105 StuntDouble * integrableObject;
106
107
108
109 kebar = kb * temperature * info_->getNdfRaw() / (2.0 * info_->getNdf());
110
111 for( mol = info_->beginMolecule(i); mol != NULL;
112 mol = info_->nextMolecule(i) ) {
113 for( integrableObject = mol->beginIntegrableObject(j);
114 integrableObject != NULL;
115 integrableObject = mol->nextIntegrableObject(j) ) {
116
117 // uses equipartition theory to solve for vbar in angstrom/fs
118
119 av2 = 2.0 * kebar / integrableObject->getMass();
120 vbar = sqrt(av2);
121
122 // picks random velocities from a gaussian distribution
123 // centered on vbar
124
125 for( int k = 0; k < 3; k++ ) {
126 aVel[k] = vbar * randNumGen_->randNorm(0.0, 1.0);
127 }
128
129 integrableObject->setVel(aVel);
130
131 if (integrableObject->isDirectional()) {
132 I = integrableObject->getI();
133
134 if (integrableObject->isLinear()) {
135 l = integrableObject->linearAxis();
136 m = (l + 1) % 3;
137 n = (l + 2) % 3;
138
139 aJ[l] = 0.0;
140 vbar = sqrt(2.0 * kebar * I(m, m));
141 aJ[m] = vbar * randNumGen_->randNorm(0.0, 1.0);
142 vbar = sqrt(2.0 * kebar * I(n, n));
143 aJ[n] = vbar * randNumGen_->randNorm(0.0, 1.0);
144 } else {
145 for( int k = 0; k < 3; k++ ) {
146 vbar = sqrt(2.0 * kebar * I(k, k));
147 aJ[k] = vbar *randNumGen_->randNorm(0.0, 1.0);
148 }
149 } // else isLinear
150
151 integrableObject->setJ(aJ);
152 } //isDirectional
153 }
154 } //end for (mol = beginMolecule(i); ...)
155
156
157
158 removeComDrift();
159 // Remove angular drift if we are not using periodic boundary conditions.
160 if(!simParams->getPBC()) removeAngularDrift();
161
162 }
163
164
165
166 void Velocitizer::removeComDrift() {
167 // Get the Center of Mass drift velocity.
168 Vector3d vdrift = info_->getComVel();
169
170 SimInfo::MoleculeIterator i;
171 Molecule::IntegrableObjectIterator j;
172 Molecule * mol;
173 StuntDouble * integrableObject;
174
175 // Corrects for the center of mass drift.
176 // sums all the momentum and divides by total mass.
177 for( mol = info_->beginMolecule(i); mol != NULL;
178 mol = info_->nextMolecule(i) ) {
179 for( integrableObject = mol->beginIntegrableObject(j);
180 integrableObject != NULL;
181 integrableObject = mol->nextIntegrableObject(j) ) {
182 integrableObject->setVel(integrableObject->getVel() - vdrift);
183 }
184 }
185
186 }
187
188
189 void Velocitizer::removeAngularDrift() {
190 // Get the Center of Mass drift velocity.
191
192 Vector3d vdrift;
193 Vector3d com;
194
195 info_->getComAll(com,vdrift);
196
197 Mat3x3d inertiaTensor;
198 Vector3d angularMomentum;
199 Vector3d omega;
200
201
202
203 info_->getInertiaTensor(inertiaTensor,angularMomentum);
204 // We now need the inverse of the inertia tensor.
205
206 std::cerr << "Angular Momentum before is "
207 << angularMomentum << std::endl;
208 std::cerr << "Inertia Tensor before is "
209 << inertiaTensor << std::endl;
210
211
212 inertiaTensor =inertiaTensor.inverse();
213 std::cerr << "Inertia Tensor after inverse is "
214 << inertiaTensor << std::endl;
215
216 omega = inertiaTensor*angularMomentum;
217
218 SimInfo::MoleculeIterator i;
219 Molecule::IntegrableObjectIterator j;
220 Molecule * mol;
221 StuntDouble * integrableObject;
222 Vector3d tempComPos;
223
224 // Corrects for the center of mass angular drift.
225 // sums all the angular momentum and divides by total mass.
226 for( mol = info_->beginMolecule(i); mol != NULL;
227 mol = info_->nextMolecule(i) ) {
228 for( integrableObject = mol->beginIntegrableObject(j);
229 integrableObject != NULL;
230 integrableObject = mol->nextIntegrableObject(j) ) {
231 tempComPos = integrableObject->getPos()-com;
232 integrableObject->setVel((integrableObject->getVel() - vdrift)-cross(omega,tempComPos));
233 }
234 }
235
236 angularMomentum = info_->getAngularMomentum();
237 std::cerr << "Angular Momentum after is "
238 << angularMomentum << std::endl;
239
240
241 }
242
243
244
245
246 }