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root/OpenMD/trunk/src/integrators/LDForceManager.cpp
Revision: 1237
Committed: Fri Apr 18 16:55:15 2008 UTC (17 years ago) by gezelter
File size: 19093 byte(s)
Log Message:
Adding iterative looping to get better estimates of friction forces
from full-step velocities

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 #include <fstream>
42 #include <iostream>
43 #include "integrators/LDForceManager.hpp"
44 #include "math/CholeskyDecomposition.hpp"
45 #include "utils/OOPSEConstant.hpp"
46 #include "hydrodynamics/Sphere.hpp"
47 #include "hydrodynamics/Ellipsoid.hpp"
48 #include "utils/ElementsTable.hpp"
49
50 namespace oopse {
51
52 LDForceManager::LDForceManager(SimInfo* info) : ForceManager(info), forceTolerance_(1e-6), maxIterNum_(4) {
53 simParams = info->getSimParams();
54 veloMunge = new Velocitizer(info);
55
56 sphericalBoundaryConditions_ = false;
57 if (simParams->getUseSphericalBoundaryConditions()) {
58 sphericalBoundaryConditions_ = true;
59 if (simParams->haveLangevinBufferRadius()) {
60 langevinBufferRadius_ = simParams->getLangevinBufferRadius();
61 } else {
62 sprintf( painCave.errMsg,
63 "langevinBufferRadius must be specified "
64 "when useSphericalBoundaryConditions is turned on.\n");
65 painCave.severity = OOPSE_ERROR;
66 painCave.isFatal = 1;
67 simError();
68 }
69
70 if (simParams->haveFrozenBufferRadius()) {
71 frozenBufferRadius_ = simParams->getFrozenBufferRadius();
72 } else {
73 sprintf( painCave.errMsg,
74 "frozenBufferRadius must be specified "
75 "when useSphericalBoundaryConditions is turned on.\n");
76 painCave.severity = OOPSE_ERROR;
77 painCave.isFatal = 1;
78 simError();
79 }
80
81 if (frozenBufferRadius_ < langevinBufferRadius_) {
82 sprintf( painCave.errMsg,
83 "frozenBufferRadius has been set smaller than the "
84 "langevinBufferRadius. This is probably an error.\n");
85 painCave.severity = OOPSE_WARNING;
86 painCave.isFatal = 0;
87 simError();
88 }
89 }
90
91 // Build the hydroProp map:
92 std::map<std::string, HydroProp*> hydroPropMap;
93
94 Molecule* mol;
95 StuntDouble* integrableObject;
96 SimInfo::MoleculeIterator i;
97 Molecule::IntegrableObjectIterator j;
98 bool needHydroPropFile = false;
99
100 for (mol = info->beginMolecule(i); mol != NULL;
101 mol = info->nextMolecule(i)) {
102 for (integrableObject = mol->beginIntegrableObject(j);
103 integrableObject != NULL;
104 integrableObject = mol->nextIntegrableObject(j)) {
105
106 if (integrableObject->isRigidBody()) {
107 RigidBody* rb = static_cast<RigidBody*>(integrableObject);
108 if (rb->getNumAtoms() > 1) needHydroPropFile = true;
109 }
110
111 }
112 }
113
114
115 if (needHydroPropFile) {
116 if (simParams->haveHydroPropFile()) {
117 hydroPropMap = parseFrictionFile(simParams->getHydroPropFile());
118 } else {
119 sprintf( painCave.errMsg,
120 "HydroPropFile must be set to a file name if Langevin Dynamics\n"
121 "\tis specified for rigidBodies which contain more than one atom\n"
122 "\tTo create a HydroPropFile, run the \"Hydro\" program.\n");
123 painCave.severity = OOPSE_ERROR;
124 painCave.isFatal = 1;
125 simError();
126 }
127
128 for (mol = info->beginMolecule(i); mol != NULL;
129 mol = info->nextMolecule(i)) {
130 for (integrableObject = mol->beginIntegrableObject(j);
131 integrableObject != NULL;
132 integrableObject = mol->nextIntegrableObject(j)) {
133
134 std::map<std::string, HydroProp*>::iterator iter = hydroPropMap.find(integrableObject->getType());
135 if (iter != hydroPropMap.end()) {
136 hydroProps_.push_back(iter->second);
137 } else {
138 sprintf( painCave.errMsg,
139 "Can not find resistance tensor for atom [%s]\n", integrableObject->getType().c_str());
140 painCave.severity = OOPSE_ERROR;
141 painCave.isFatal = 1;
142 simError();
143 }
144 }
145 }
146 } else {
147
148 std::map<std::string, HydroProp*> hydroPropMap;
149 for (mol = info->beginMolecule(i); mol != NULL;
150 mol = info->nextMolecule(i)) {
151 for (integrableObject = mol->beginIntegrableObject(j);
152 integrableObject != NULL;
153 integrableObject = mol->nextIntegrableObject(j)) {
154 Shape* currShape = NULL;
155
156 if (integrableObject->isAtom()){
157 Atom* atom = static_cast<Atom*>(integrableObject);
158 AtomType* atomType = atom->getAtomType();
159 if (atomType->isGayBerne()) {
160 DirectionalAtomType* dAtomType = dynamic_cast<DirectionalAtomType*>(atomType);
161 GenericData* data = dAtomType->getPropertyByName("GayBerne");
162 if (data != NULL) {
163 GayBerneParamGenericData* gayBerneData = dynamic_cast<GayBerneParamGenericData*>(data);
164
165 if (gayBerneData != NULL) {
166 GayBerneParam gayBerneParam = gayBerneData->getData();
167 currShape = new Ellipsoid(V3Zero,
168 gayBerneParam.GB_l / 2.0,
169 gayBerneParam.GB_d / 2.0,
170 Mat3x3d::identity());
171 } else {
172 sprintf( painCave.errMsg,
173 "Can not cast GenericData to GayBerneParam\n");
174 painCave.severity = OOPSE_ERROR;
175 painCave.isFatal = 1;
176 simError();
177 }
178 } else {
179 sprintf( painCave.errMsg, "Can not find Parameters for GayBerne\n");
180 painCave.severity = OOPSE_ERROR;
181 painCave.isFatal = 1;
182 simError();
183 }
184 } else {
185 if (atomType->isLennardJones()){
186 GenericData* data = atomType->getPropertyByName("LennardJones");
187 if (data != NULL) {
188 LJParamGenericData* ljData = dynamic_cast<LJParamGenericData*>(data);
189 if (ljData != NULL) {
190 LJParam ljParam = ljData->getData();
191 currShape = new Sphere(atom->getPos(), ljParam.sigma/2.0);
192 } else {
193 sprintf( painCave.errMsg,
194 "Can not cast GenericData to LJParam\n");
195 painCave.severity = OOPSE_ERROR;
196 painCave.isFatal = 1;
197 simError();
198 }
199 }
200 } else {
201 int aNum = etab.GetAtomicNum((atom->getType()).c_str());
202 if (aNum != 0) {
203 currShape = new Sphere(atom->getPos(), etab.GetVdwRad(aNum));
204 } else {
205 sprintf( painCave.errMsg,
206 "Could not find atom type in default element.txt\n");
207 painCave.severity = OOPSE_ERROR;
208 painCave.isFatal = 1;
209 simError();
210 }
211 }
212 }
213 }
214 HydroProp* currHydroProp = currShape->getHydroProp(simParams->getViscosity(),simParams->getTargetTemp());
215 std::map<std::string, HydroProp*>::iterator iter = hydroPropMap.find(integrableObject->getType());
216 if (iter != hydroPropMap.end())
217 hydroProps_.push_back(iter->second);
218 else {
219 currHydroProp->complete();
220 hydroPropMap.insert(std::map<std::string, HydroProp*>::value_type(integrableObject->getType(), currHydroProp));
221 hydroProps_.push_back(currHydroProp);
222 }
223 }
224 }
225 }
226 variance_ = 2.0 * OOPSEConstant::kb*simParams->getTargetTemp()/simParams->getDt();
227 }
228
229 std::map<std::string, HydroProp*> LDForceManager::parseFrictionFile(const std::string& filename) {
230 std::map<std::string, HydroProp*> props;
231 std::ifstream ifs(filename.c_str());
232 if (ifs.is_open()) {
233
234 }
235
236 const unsigned int BufferSize = 65535;
237 char buffer[BufferSize];
238 while (ifs.getline(buffer, BufferSize)) {
239 HydroProp* currProp = new HydroProp(buffer);
240 props.insert(std::map<std::string, HydroProp*>::value_type(currProp->getName(), currProp));
241 }
242
243 return props;
244 }
245
246 void LDForceManager::postCalculation(bool needStress){
247 SimInfo::MoleculeIterator i;
248 Molecule::IntegrableObjectIterator j;
249 Molecule* mol;
250 StuntDouble* integrableObject;
251 RealType mass;
252 Vector3d pos;
253 Vector3d frc;
254 Mat3x3d A;
255 Mat3x3d Atrans;
256 Vector3d Tb;
257 Vector3d ji;
258 unsigned int index = 0;
259 bool doLangevinForces;
260 bool freezeMolecule;
261 int fdf;
262
263 fdf = 0;
264
265 for (mol = info_->beginMolecule(i); mol != NULL; mol = info_->nextMolecule(i)) {
266
267 doLangevinForces = true;
268 freezeMolecule = false;
269
270 if (sphericalBoundaryConditions_) {
271
272 Vector3d molPos = mol->getCom();
273 RealType molRad = molPos.length();
274
275 doLangevinForces = false;
276
277 if (molRad > langevinBufferRadius_) {
278 doLangevinForces = true;
279 freezeMolecule = false;
280 }
281 if (molRad > frozenBufferRadius_) {
282 doLangevinForces = false;
283 freezeMolecule = true;
284 }
285 }
286
287 for (integrableObject = mol->beginIntegrableObject(j); integrableObject != NULL;
288 integrableObject = mol->nextIntegrableObject(j)) {
289
290 if (freezeMolecule)
291 fdf += integrableObject->freeze();
292
293 if (doLangevinForces) {
294 mass = integrableObject->getMass();
295 if (integrableObject->isDirectional()){
296
297 // preliminaries for directional objects:
298
299 A = integrableObject->getA();
300 Atrans = A.transpose();
301 Vector3d rcrLab = Atrans * hydroProps_[index]->getCOR();
302
303 //apply random force and torque at center of resistance
304
305 Vector3d randomForceBody;
306 Vector3d randomTorqueBody;
307 genRandomForceAndTorque(randomForceBody, randomTorqueBody, index, variance_);
308 Vector3d randomForceLab = Atrans * randomForceBody;
309 Vector3d randomTorqueLab = Atrans * randomTorqueBody;
310 integrableObject->addFrc(randomForceLab);
311 integrableObject->addTrq(randomTorqueLab + cross(rcrLab, randomForceLab ));
312
313 Mat3x3d I = integrableObject->getI();
314 Vector3d omegaBody;
315
316 // What remains contains velocity explicitly, but the velocity required
317 // is at the full step: v(t + h), while we have initially the velocity
318 // at the half step: v(t + h/2). We need to iterate to converge the
319 // friction force and friction torque vectors.
320
321 // this is the velocity at the half-step:
322
323 Vector3d vel =integrableObject->getVel();
324 Vector3d angMom = integrableObject->getJ();
325
326 //estimate velocity at full-step using everything but friction forces:
327
328 frc = integrableObject->getFrc();
329 Vector3d velStep = vel + (dt2_ /mass * OOPSEConstant::energyConvert) * frc;
330
331 Tb = integrableObject->lab2Body(integrableObject->getTrq());
332 Vector3d angMomStep = angMom + (dt2_ * OOPSEConstant::energyConvert) * Tb;
333
334 Vector3d omegaLab;
335 Vector3d vcdLab;
336 Vector3d vcdBody;
337 Vector3d frictionForceBody;
338 Vector3d frictionForceLab(0.0);
339 Vector3d oldFFL; // used to test for convergence
340 Vector3d frictionTorqueBody(0.0);
341 Vector3d oldFTB; // used to test for convergence
342 Vector3d frictionTorqueLab;
343 RealType fdot;
344 RealType tdot;
345
346 //iteration starts here:
347
348 for (int k = 0; k < maxIterNum_; k++) {
349
350 if (integrableObject->isLinear()) {
351 int linearAxis = integrableObject->linearAxis();
352 int l = (linearAxis +1 )%3;
353 int m = (linearAxis +2 )%3;
354 omegaBody[l] = angMomStep[l] /I(l, l);
355 omegaBody[m] = angMomStep[m] /I(m, m);
356
357 } else {
358 omegaBody[0] = angMomStep[0] /I(0, 0);
359 omegaBody[1] = angMomStep[1] /I(1, 1);
360 omegaBody[2] = angMomStep[2] /I(2, 2);
361 }
362
363 omegaLab = Atrans * omegaBody;
364
365 // apply friction force and torque at center of resistance
366
367 vcdLab = velStep + cross(omegaLab, rcrLab);
368 vcdBody = A * vcdLab;
369 frictionForceBody = -(hydroProps_[index]->getXitt() * vcdBody + hydroProps_[index]->getXirt() * omegaBody);
370 oldFFL = frictionForceLab;
371 frictionForceLab = Atrans * frictionForceBody;
372 oldFTB = frictionTorqueBody;
373 frictionTorqueBody = -(hydroProps_[index]->getXitr() * vcdBody + hydroProps_[index]->getXirr() * omegaBody);
374 frictionTorqueLab = Atrans * frictionTorqueBody;
375
376 // re-estimate velocities at full-step using friction forces:
377
378 velStep = vel + (dt2_ / mass * OOPSEConstant::energyConvert) * (frc + frictionForceLab);
379 angMomStep = angMom + (dt2_ * OOPSEConstant::energyConvert) * (Tb + frictionTorqueBody);
380
381 // check for convergence (if the vectors have converged, fdot and tdot will both be 1.0):
382
383 fdot = dot(frictionForceLab, oldFFL) / frictionForceLab.lengthSquare();
384 tdot = dot(frictionTorqueBody, oldFTB) / frictionTorqueBody.lengthSquare();
385
386 if (fabs(1.0 - fdot) <= forceTolerance_ && fabs(1.0 - tdot) <= forceTolerance_)
387 break; // iteration ends here
388 }
389
390 integrableObject->addFrc(frictionForceLab);
391 integrableObject->addTrq(frictionTorqueLab + cross(rcrLab, frictionForceLab));
392
393
394 } else {
395 //spherical atom
396
397 Vector3d randomForce;
398 Vector3d randomTorque;
399 genRandomForceAndTorque(randomForce, randomTorque, index, variance_);
400 integrableObject->addFrc(randomForce);
401
402 // What remains contains velocity explicitly, but the velocity required
403 // is at the full step: v(t + h), while we have initially the velocity
404 // at the half step: v(t + h/2). We need to iterate to converge the
405 // friction force vector.
406
407 // this is the velocity at the half-step:
408
409 Vector3d vel =integrableObject->getVel();
410
411 //estimate velocity at full-step using everything but friction forces:
412
413 frc = integrableObject->getFrc();
414 Vector3d velStep = vel + (dt2_ / mass * OOPSEConstant::energyConvert) * frc;
415
416 Vector3d frictionForce(0.0);
417 Vector3d oldFF; // used to test for convergence
418 RealType fdot;
419
420 //iteration starts here:
421
422 for (int k = 0; k < maxIterNum_; k++) {
423
424 oldFF = frictionForce;
425 frictionForce = -hydroProps_[index]->getXitt() * velStep;
426
427 // re-estimate velocities at full-step using friction forces:
428
429 velStep = vel + (dt2_ / mass * OOPSEConstant::energyConvert) * (frc + frictionForce);
430
431 // check for convergence (if the vector has converged, fdot will be 1.0):
432
433 fdot = dot(frictionForce, oldFF) / frictionForce.lengthSquare();
434
435 if (fabs(1.0 - fdot) <= forceTolerance_)
436 break; // iteration ends here
437 }
438
439 integrableObject->addFrc(frictionForce);
440
441 }
442 }
443
444 ++index;
445
446 }
447 }
448
449 info_->setFdf(fdf);
450 veloMunge->removeComDrift();
451 // Remove angular drift if we are not using periodic boundary conditions.
452 if(!simParams->getUsePeriodicBoundaryConditions())
453 veloMunge->removeAngularDrift();
454
455 ForceManager::postCalculation(needStress);
456 }
457
458 void LDForceManager::genRandomForceAndTorque(Vector3d& force, Vector3d& torque, unsigned int index, RealType variance) {
459
460
461 Vector<RealType, 6> Z;
462 Vector<RealType, 6> generalForce;
463
464 Z[0] = randNumGen_.randNorm(0, variance);
465 Z[1] = randNumGen_.randNorm(0, variance);
466 Z[2] = randNumGen_.randNorm(0, variance);
467 Z[3] = randNumGen_.randNorm(0, variance);
468 Z[4] = randNumGen_.randNorm(0, variance);
469 Z[5] = randNumGen_.randNorm(0, variance);
470
471 generalForce = hydroProps_[index]->getS()*Z;
472
473 force[0] = generalForce[0];
474 force[1] = generalForce[1];
475 force[2] = generalForce[2];
476 torque[0] = generalForce[3];
477 torque[1] = generalForce[4];
478 torque[2] = generalForce[5];
479
480 }
481
482 }

Properties

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svn:executable *