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root/group/trunk/OOPSE/libmdtools/NPTi.cpp
Revision: 768
Committed: Wed Sep 17 14:22:15 2003 UTC (20 years, 9 months ago) by mmeineke
File size: 9679 byte(s)
Log Message:
fixed NPTi to now work with constraints.

File Contents

# Content
1 #include <cmath>
2 #include "Atom.hpp"
3 #include "SRI.hpp"
4 #include "AbstractClasses.hpp"
5 #include "SimInfo.hpp"
6 #include "ForceFields.hpp"
7 #include "Thermo.hpp"
8 #include "ReadWrite.hpp"
9 #include "Integrator.hpp"
10 #include "simError.h"
11
12 #ifdef IS_MPI
13 #include "mpiSimulation.hpp"
14 #endif
15
16
17 // Basic isotropic thermostating and barostating via the Melchionna
18 // modification of the Hoover algorithm:
19 //
20 // Melchionna, S., Ciccotti, G., and Holian, B. L., 1993,
21 // Molec. Phys., 78, 533.
22 //
23 // and
24 //
25 // Hoover, W. G., 1986, Phys. Rev. A, 34, 2499.
26
27 template<typename T> NPTi<T>::NPTi ( SimInfo *theInfo, ForceFields* the_ff):
28 T( theInfo, the_ff )
29 {
30 chi = 0.0;
31 eta = 0.0;
32 integralOfChidt = 0.0;
33 have_tau_thermostat = 0;
34 have_tau_barostat = 0;
35 have_target_temp = 0;
36 have_target_pressure = 0;
37 have_chi_tolerance = 0;
38 have_eta_tolerance = 0;
39 have_pos_iter_tolerance = 0;
40
41 oldPos = new double[3*nAtoms];
42 oldVel = new double[3*nAtoms];
43 oldJi = new double[3*nAtoms];
44 #ifdef IS_MPI
45 Nparticles = mpiSim->getTotAtoms();
46 #else
47 Nparticles = theInfo->n_atoms;
48 #endif
49
50 }
51
52 template<typename T> NPTi<T>::~NPTi() {
53 delete[] oldPos;
54 delete[] oldVel;
55 delete[] oldJi;
56 }
57
58 template<typename T> void NPTi<T>::moveA() {
59
60 //new version of NPTi
61 int i, j, k;
62 DirectionalAtom* dAtom;
63 double Tb[3], ji[3];
64 double A[3][3], I[3][3];
65 double angle, mass;
66 double vel[3], pos[3], frc[3];
67
68 double rj[3];
69 double instaTemp, instaPress, instaVol;
70 double tt2, tb2, scaleFactor;
71 double COM[3];
72
73 tt2 = tauThermostat * tauThermostat;
74 tb2 = tauBarostat * tauBarostat;
75
76 instaTemp = tStats->getTemperature();
77 instaPress = tStats->getPressure();
78 instaVol = tStats->getVolume();
79
80 tStats->getCOM(COM);
81
82 //evolve velocity half step
83 for( i=0; i<nAtoms; i++ ){
84
85 atoms[i]->getVel( vel );
86 atoms[i]->getFrc( frc );
87
88 mass = atoms[i]->getMass();
89
90 for (j=0; j < 3; j++) {
91 // velocity half step (use chi from previous step here):
92 vel[j] += dt2 * ((frc[j] / mass ) * eConvert - vel[j]*(chi + eta));
93
94 }
95
96 atoms[i]->setVel( vel );
97
98 if( atoms[i]->isDirectional() ){
99
100 dAtom = (DirectionalAtom *)atoms[i];
101
102 // get and convert the torque to body frame
103
104 dAtom->getTrq( Tb );
105 dAtom->lab2Body( Tb );
106
107 // get the angular momentum, and propagate a half step
108
109 dAtom->getJ( ji );
110
111 for (j=0; j < 3; j++)
112 ji[j] += dt2 * (Tb[j] * eConvert - ji[j]*chi);
113
114 // use the angular velocities to propagate the rotation matrix a
115 // full time step
116
117 dAtom->getA(A);
118 dAtom->getI(I);
119
120 // rotate about the x-axis
121 angle = dt2 * ji[0] / I[0][0];
122 this->rotate( 1, 2, angle, ji, A );
123
124 // rotate about the y-axis
125 angle = dt2 * ji[1] / I[1][1];
126 this->rotate( 2, 0, angle, ji, A );
127
128 // rotate about the z-axis
129 angle = dt * ji[2] / I[2][2];
130 this->rotate( 0, 1, angle, ji, A);
131
132 // rotate about the y-axis
133 angle = dt2 * ji[1] / I[1][1];
134 this->rotate( 2, 0, angle, ji, A );
135
136 // rotate about the x-axis
137 angle = dt2 * ji[0] / I[0][0];
138 this->rotate( 1, 2, angle, ji, A );
139
140 dAtom->setJ( ji );
141 dAtom->setA( A );
142 }
143 }
144
145 // evolve chi and eta half step
146
147 chi += dt2 * ( instaTemp / targetTemp - 1.0) / tt2;
148 eta += dt2 * ( instaVol * (instaPress - targetPressure) / (p_convert*NkBT*tb2));
149
150 //calculate the integral of chidt
151 integralOfChidt += dt2*chi;
152
153 //save the old positions
154 for(i = 0; i < nAtoms; i++){
155 atoms[i]->getPos(pos);
156 for(j = 0; j < 3; j++)
157 oldPos[i*3 + j] = pos[j];
158 }
159
160 //the first estimation of r(t+dt) is equal to r(t)
161
162 for(k = 0; k < 4; k ++){
163
164 for(i =0 ; i < nAtoms; i++){
165
166 atoms[i]->getVel(vel);
167 atoms[i]->getPos(pos);
168
169 for(j = 0; j < 3; j++)
170 rj[j] = (oldPos[i*3 + j] + pos[j])/2 - COM[j];
171
172 for(j = 0; j < 3; j++)
173 pos[j] = oldPos[i*3 + j] + dt*(vel[j] + eta*rj[j]);
174
175 atoms[i]->setPos( pos );
176 }
177
178 if (nConstrained){
179 constrainA();
180 }
181 }
182
183
184 // Scale the box after all the positions have been moved:
185
186 scaleFactor = exp(dt*eta);
187
188 if ((scaleFactor > 1.1) || (scaleFactor < 0.9)) {
189 sprintf( painCave.errMsg,
190 "NPTi error: Attempting a Box scaling of more than 10 percent"
191 " check your tauBarostat, as it is probably too small!\n"
192 " eta = %lf, scaleFactor = %lf\n", eta, scaleFactor
193 );
194 painCave.isFatal = 1;
195 simError();
196 } else {
197 info->scaleBox(scaleFactor);
198 }
199
200 }
201
202 template<typename T> void NPTi<T>::moveB( void ){
203
204 //new version of NPTi
205 int i, j, k;
206 DirectionalAtom* dAtom;
207 double Tb[3], ji[3];
208 double vel[3], frc[3];
209 double mass;
210
211 double instTemp, instPress, instVol;
212 double tt2, tb2;
213 double oldChi, prevChi;
214 double oldEta, preEta;
215
216 tt2 = tauThermostat * tauThermostat;
217 tb2 = tauBarostat * tauBarostat;
218
219
220 // Set things up for the iteration:
221
222 oldChi = chi;
223 oldEta = eta;
224
225 for( i=0; i<nAtoms; i++ ){
226
227 atoms[i]->getVel( vel );
228
229 for (j=0; j < 3; j++)
230 oldVel[3*i + j] = vel[j];
231
232 if( atoms[i]->isDirectional() ){
233
234 dAtom = (DirectionalAtom *)atoms[i];
235
236 dAtom->getJ( ji );
237
238 for (j=0; j < 3; j++)
239 oldJi[3*i + j] = ji[j];
240
241 }
242 }
243
244 // do the iteration:
245
246 instVol = tStats->getVolume();
247
248 for (k=0; k < 4; k++) {
249
250 instTemp = tStats->getTemperature();
251 instPress = tStats->getPressure();
252
253 // evolve chi another half step using the temperature at t + dt/2
254
255 prevChi = chi;
256 chi = oldChi + dt2 * ( instTemp / targetTemp - 1.0) /
257 (tauThermostat*tauThermostat);
258
259 preEta = eta;
260 eta = oldEta + dt2 * ( instVol * (instPress - targetPressure) /
261 (p_convert*NkBT*tb2));
262
263
264 for( i=0; i<nAtoms; i++ ){
265
266 atoms[i]->getFrc( frc );
267 atoms[i]->getVel(vel);
268
269 mass = atoms[i]->getMass();
270
271 // velocity half step
272 for (j=0; j < 3; j++)
273 vel[j] = oldVel[3*i+j] + dt2 * ((frc[j] / mass ) * eConvert - oldVel[3*i + j]*(chi + eta));
274
275 atoms[i]->setVel( vel );
276
277 if( atoms[i]->isDirectional() ){
278
279 dAtom = (DirectionalAtom *)atoms[i];
280
281 // get and convert the torque to body frame
282
283 dAtom->getTrq( Tb );
284 dAtom->lab2Body( Tb );
285
286 for (j=0; j < 3; j++)
287 ji[j] = oldJi[3*i + j] + dt2 * (Tb[j] * eConvert - oldJi[3*i+j]*chi);
288
289 dAtom->setJ( ji );
290 }
291 }
292
293 if (nConstrained){
294 constrainB();
295 }
296
297 if (fabs(prevChi - chi) <=
298 chiTolerance && fabs(preEta -eta) <= etaTolerance)
299 break;
300 }
301
302 //calculate integral of chida
303 integralOfChidt += dt2*chi;
304
305
306 }
307
308 template<typename T> void NPTi<T>::resetIntegrator() {
309 chi = 0.0;
310 eta = 0.0;
311 }
312
313 template<typename T> int NPTi<T>::readyCheck() {
314
315 //check parent's readyCheck() first
316 if (T::readyCheck() == -1)
317 return -1;
318
319 // First check to see if we have a target temperature.
320 // Not having one is fatal.
321
322 if (!have_target_temp) {
323 sprintf( painCave.errMsg,
324 "NPTi error: You can't use the NPTi integrator\n"
325 " without a targetTemp!\n"
326 );
327 painCave.isFatal = 1;
328 simError();
329 return -1;
330 }
331
332 if (!have_target_pressure) {
333 sprintf( painCave.errMsg,
334 "NPTi error: You can't use the NPTi integrator\n"
335 " without a targetPressure!\n"
336 );
337 painCave.isFatal = 1;
338 simError();
339 return -1;
340 }
341
342 // We must set tauThermostat.
343
344 if (!have_tau_thermostat) {
345 sprintf( painCave.errMsg,
346 "NPTi error: If you use the NPTi\n"
347 " integrator, you must set tauThermostat.\n");
348 painCave.isFatal = 1;
349 simError();
350 return -1;
351 }
352
353 // We must set tauBarostat.
354
355 if (!have_tau_barostat) {
356 sprintf( painCave.errMsg,
357 "NPTi error: If you use the NPTi\n"
358 " integrator, you must set tauBarostat.\n");
359 painCave.isFatal = 1;
360 simError();
361 return -1;
362 }
363
364 if (!have_chi_tolerance) {
365 sprintf( painCave.errMsg,
366 "NPTi warning: setting chi tolerance to 1e-6\n");
367 chiTolerance = 1e-6;
368 have_chi_tolerance = 1;
369 painCave.isFatal = 0;
370 simError();
371 }
372
373 if (!have_eta_tolerance) {
374 sprintf( painCave.errMsg,
375 "NPTi warning: setting eta tolerance to 1e-6\n");
376 etaTolerance = 1e-6;
377 have_eta_tolerance = 1;
378 painCave.isFatal = 0;
379 simError();
380 }
381 // We need NkBT a lot, so just set it here:
382
383 NkBT = (double)Nparticles * kB * targetTemp;
384 fkBT = (double)info->ndf * kB * targetTemp;
385
386 return 1;
387 }
388
389 template<typename T> double NPTi<T>::getConservedQuantity(void){
390
391 double conservedQuantity;
392 double tb2;
393 double eta2;
394 double E_NPT;
395 double U;
396 double TS;
397 double PV;
398 double extra;
399
400 U = tStats->getTotalE();
401
402 TS = fkBT *
403 (integralOfChidt + tauThermostat * tauThermostat * chi * chi / 2.0) / eConvert;
404
405 PV = (targetPressure * tStats->getVolume() / p_convert) / eConvert;
406
407 tb2 = tauBarostat * tauBarostat;
408 eta2 = eta * eta;
409
410
411 extra = ((double)info->ndfTrans * kB * targetTemp * tb2 * eta2 / 2.0) / eConvert;
412
413 cout.width(8);
414 cout.precision(8);
415
416
417 // cout << info->getTime() << "\t"
418 // << chi << "\t"
419 // << eta << "\t"
420 // << U << "\t"
421 // << TS << "\t"
422 // << PV << "\t"
423 // << extra << "\t"
424 // << U+TS+PV+extra << endl;
425
426 conservedQuantity = U+TS+PV+extra;
427 return conservedQuantity;
428 }