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root/group/trunk/OOPSE/libmdtools/NPTi.cpp
Revision: 770
Committed: Fri Sep 19 14:55:41 2003 UTC (20 years, 9 months ago) by gezelter
File size: 10250 byte(s)
Log Message:
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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 // Set things up for the iteration:
220
221 oldChi = chi;
222 oldEta = eta;
223
224 for( i=0; i<nAtoms; i++ ){
225
226 atoms[i]->getVel( vel );
227
228 for (j=0; j < 3; j++)
229 oldVel[3*i + j] = vel[j];
230
231 if( atoms[i]->isDirectional() ){
232
233 dAtom = (DirectionalAtom *)atoms[i];
234
235 dAtom->getJ( ji );
236
237 for (j=0; j < 3; j++)
238 oldJi[3*i + j] = ji[j];
239
240 }
241 }
242
243 // do the iteration:
244
245 instVol = tStats->getVolume();
246
247 for (k=0; k < 4; k++) {
248
249 instTemp = tStats->getTemperature();
250 instPress = tStats->getPressure();
251
252 // evolve chi another half step using the temperature at t + dt/2
253
254 prevChi = chi;
255 chi = oldChi + dt2 * ( instTemp / targetTemp - 1.0) /
256 (tauThermostat*tauThermostat);
257
258 preEta = eta;
259 eta = oldEta + dt2 * ( instVol * (instPress - targetPressure) /
260 (p_convert*NkBT*tb2));
261
262
263 for( i=0; i<nAtoms; i++ ){
264
265 atoms[i]->getFrc( frc );
266 atoms[i]->getVel(vel);
267
268 mass = atoms[i]->getMass();
269
270 // velocity half step
271 for (j=0; j < 3; j++)
272 vel[j] = oldVel[3*i+j] + dt2 * ((frc[j] / mass ) * eConvert - oldVel[3*i + j]*(chi + eta));
273
274 atoms[i]->setVel( vel );
275
276 if( atoms[i]->isDirectional() ){
277
278 dAtom = (DirectionalAtom *)atoms[i];
279
280 // get and convert the torque to body frame
281
282 dAtom->getTrq( Tb );
283 dAtom->lab2Body( Tb );
284
285 for (j=0; j < 3; j++)
286 ji[j] = oldJi[3*i + j] + dt2 * (Tb[j] * eConvert - oldJi[3*i+j]*chi);
287
288 dAtom->setJ( ji );
289 }
290 }
291
292 if (nConstrained){
293 constrainB();
294 }
295
296 if (fabs(prevChi - chi) <=
297 chiTolerance && fabs(preEta -eta) <= etaTolerance)
298 break;
299 }
300
301 //calculate integral of chida
302 integralOfChidt += dt2*chi;
303
304
305 }
306
307 template<typename T> void NPTi<T>::resetIntegrator() {
308 chi = 0.0;
309 eta = 0.0;
310 }
311
312 template<typename T> int NPTi<T>::readyCheck() {
313
314 //check parent's readyCheck() first
315 if (T::readyCheck() == -1)
316 return -1;
317
318 // First check to see if we have a target temperature.
319 // Not having one is fatal.
320
321 if (!have_target_temp) {
322 sprintf( painCave.errMsg,
323 "NPTi error: You can't use the NPTi integrator\n"
324 " without a targetTemp!\n"
325 );
326 painCave.isFatal = 1;
327 simError();
328 return -1;
329 }
330
331 if (!have_target_pressure) {
332 sprintf( painCave.errMsg,
333 "NPTi error: You can't use the NPTi integrator\n"
334 " without a targetPressure!\n"
335 );
336 painCave.isFatal = 1;
337 simError();
338 return -1;
339 }
340
341 // We must set tauThermostat.
342
343 if (!have_tau_thermostat) {
344 sprintf( painCave.errMsg,
345 "NPTi error: If you use the NPTi\n"
346 " integrator, you must set tauThermostat.\n");
347 painCave.isFatal = 1;
348 simError();
349 return -1;
350 }
351
352 // We must set tauBarostat.
353
354 if (!have_tau_barostat) {
355 sprintf( painCave.errMsg,
356 "NPTi error: If you use the NPTi\n"
357 " integrator, you must set tauBarostat.\n");
358 painCave.isFatal = 1;
359 simError();
360 return -1;
361 }
362
363 if (!have_chi_tolerance) {
364 sprintf( painCave.errMsg,
365 "NPTi warning: setting chi tolerance to 1e-6\n");
366 chiTolerance = 1e-6;
367 have_chi_tolerance = 1;
368 painCave.isFatal = 0;
369 simError();
370 }
371
372 if (!have_eta_tolerance) {
373 sprintf( painCave.errMsg,
374 "NPTi warning: setting eta tolerance to 1e-6\n");
375 etaTolerance = 1e-6;
376 have_eta_tolerance = 1;
377 painCave.isFatal = 0;
378 simError();
379 }
380
381
382 // We need NkBT a lot, so just set it here: This is the RAW number
383 // of particles, so no subtraction or addition of constraints or
384 // orientational degrees of freedom:
385
386 NkBT = (double)Nparticles * kB * targetTemp;
387
388 // fkBT is used because the thermostat operates on more degrees of freedom
389 // than the barostat (when there are particles with orientational degrees
390 // of freedom). ndf = 3 * (n_atoms + n_oriented -1) - n_constraint - nZcons
391
392 fkBT = (double)info->ndf * kB * targetTemp;
393
394 return 1;
395 }
396
397 template<typename T> double NPTi<T>::getConservedQuantity(void){
398
399 double conservedQuantity;
400 double Three_NkBT;
401 double Energy;
402 double thermostat_kinetic;
403 double thermostat_potential;
404 double barostat_kinetic;
405 double barostat_potential;
406 double tb2;
407 double eta2;
408
409 Energy = tStats->getTotalE();
410
411 thermostat_kinetic = fkBT* tauThermostat * tauThermostat * chi * chi /
412 (2.0 * eConvert);
413
414 thermostat_potential = fkBT* integralOfChidt / eConvert;
415
416
417 barostat_kinetic = 3.0 * NkBT * tauBarostat * tauBarostat * eta * eta /
418 (2.0 * eConvert);
419
420 barostat_potential = (targetPressure * tStats->getVolume() / p_convert) /
421 eConvert;
422
423 conservedQuantity = Energy + thermostat_kinetic + thermostat_potential +
424 barostat_kinetic + barostat_potential;
425
426 cout.width(8);
427 cout.precision(8);
428
429 cerr << info->getTime() << "\t" << Energy << "\t" << thermostat_kinetic <<
430 "\t" << thermostat_potential << "\t" << barostat_kinetic <<
431 "\t" << barostat_potential << "\t" << conservedQuantity << endl;
432
433 return conservedQuantity;
434 }