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root/group/trunk/OOPSE/libmdtools/NPTi.cpp
Revision: 767
Committed: Tue Sep 16 20:02:11 2003 UTC (20 years, 9 months ago) by tim
File size: 9539 byte(s)
Log Message:
fixed ecr grow in SimInfo

fixed conserved quantity in NPT (Still some small bug)

NPTi appears very stable.

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
179 }
180
181
182 // Scale the box after all the positions have been moved:
183
184 scaleFactor = exp(dt*eta);
185
186 if ((scaleFactor > 1.1) || (scaleFactor < 0.9)) {
187 sprintf( painCave.errMsg,
188 "NPTi error: Attempting a Box scaling of more than 10 percent"
189 " check your tauBarostat, as it is probably too small!\n"
190 " eta = %lf, scaleFactor = %lf\n", eta, scaleFactor
191 );
192 painCave.isFatal = 1;
193 simError();
194 } else {
195 info->scaleBox(scaleFactor);
196 }
197
198 }
199
200 template<typename T> void NPTi<T>::moveB( void ){
201
202 //new version of NPTi
203 int i, j, k;
204 DirectionalAtom* dAtom;
205 double Tb[3], ji[3];
206 double vel[3], frc[3];
207 double mass;
208
209 double instTemp, instPress, instVol;
210 double tt2, tb2;
211 double oldChi, prevChi;
212 double oldEta, preEta;
213
214 tt2 = tauThermostat * tauThermostat;
215 tb2 = tauBarostat * tauBarostat;
216
217
218 // Set things up for the iteration:
219
220 oldChi = chi;
221 oldEta = eta;
222
223 for( i=0; i<nAtoms; i++ ){
224
225 atoms[i]->getVel( vel );
226
227 for (j=0; j < 3; j++)
228 oldVel[3*i + j] = vel[j];
229
230 if( atoms[i]->isDirectional() ){
231
232 dAtom = (DirectionalAtom *)atoms[i];
233
234 dAtom->getJ( ji );
235
236 for (j=0; j < 3; j++)
237 oldJi[3*i + j] = ji[j];
238
239 }
240 }
241
242 // do the iteration:
243
244 instVol = tStats->getVolume();
245
246 for (k=0; k < 4; k++) {
247
248 instTemp = tStats->getTemperature();
249 instPress = tStats->getPressure();
250
251 // evolve chi another half step using the temperature at t + dt/2
252
253 prevChi = chi;
254 chi = oldChi + dt2 * ( instTemp / targetTemp - 1.0) /
255 (tauThermostat*tauThermostat);
256
257 preEta = eta;
258 eta = oldEta + dt2 * ( instVol * (instPress - targetPressure) /
259 (p_convert*NkBT*tb2));
260
261
262 for( i=0; i<nAtoms; i++ ){
263
264 atoms[i]->getFrc( frc );
265 atoms[i]->getVel(vel);
266
267 mass = atoms[i]->getMass();
268
269 // velocity half step
270 for (j=0; j < 3; j++)
271 vel[j] = oldVel[3*i+j] + dt2 * ((frc[j] / mass ) * eConvert - oldVel[3*i + j]*(chi + eta));
272
273 atoms[i]->setVel( vel );
274
275 if( atoms[i]->isDirectional() ){
276
277 dAtom = (DirectionalAtom *)atoms[i];
278
279 // get and convert the torque to body frame
280
281 dAtom->getTrq( Tb );
282 dAtom->lab2Body( Tb );
283
284 for (j=0; j < 3; j++)
285 ji[j] = oldJi[3*i + j] + dt2 * (Tb[j] * eConvert - oldJi[3*i+j]*chi);
286
287 dAtom->setJ( ji );
288 }
289 }
290
291 if (fabs(prevChi - chi) <= chiTolerance && fabs(preEta -eta) <= etaTolerance)
292 break;
293 }
294
295 //calculate integral of chida
296 integralOfChidt += dt2*chi;
297
298
299 }
300
301 template<typename T> void NPTi<T>::resetIntegrator() {
302 chi = 0.0;
303 eta = 0.0;
304 }
305
306 template<typename T> int NPTi<T>::readyCheck() {
307
308 //check parent's readyCheck() first
309 if (T::readyCheck() == -1)
310 return -1;
311
312 // First check to see if we have a target temperature.
313 // Not having one is fatal.
314
315 if (!have_target_temp) {
316 sprintf( painCave.errMsg,
317 "NPTi error: You can't use the NPTi integrator\n"
318 " without a targetTemp!\n"
319 );
320 painCave.isFatal = 1;
321 simError();
322 return -1;
323 }
324
325 if (!have_target_pressure) {
326 sprintf( painCave.errMsg,
327 "NPTi error: You can't use the NPTi integrator\n"
328 " without a targetPressure!\n"
329 );
330 painCave.isFatal = 1;
331 simError();
332 return -1;
333 }
334
335 // We must set tauThermostat.
336
337 if (!have_tau_thermostat) {
338 sprintf( painCave.errMsg,
339 "NPTi error: If you use the NPTi\n"
340 " integrator, you must set tauThermostat.\n");
341 painCave.isFatal = 1;
342 simError();
343 return -1;
344 }
345
346 // We must set tauBarostat.
347
348 if (!have_tau_barostat) {
349 sprintf( painCave.errMsg,
350 "NPTi error: If you use the NPTi\n"
351 " integrator, you must set tauBarostat.\n");
352 painCave.isFatal = 1;
353 simError();
354 return -1;
355 }
356
357 if (!have_chi_tolerance) {
358 sprintf( painCave.errMsg,
359 "NPTi warning: setting chi tolerance to 1e-6\n");
360 chiTolerance = 1e-6;
361 have_chi_tolerance = 1;
362 painCave.isFatal = 0;
363 simError();
364 }
365
366 if (!have_eta_tolerance) {
367 sprintf( painCave.errMsg,
368 "NPTi warning: setting eta tolerance to 1e-6\n");
369 etaTolerance = 1e-6;
370 have_eta_tolerance = 1;
371 painCave.isFatal = 0;
372 simError();
373 }
374 // We need NkBT a lot, so just set it here:
375
376 NkBT = (double)Nparticles * kB * targetTemp;
377 fkBT = (double)info->ndf * kB * targetTemp;
378
379 return 1;
380 }
381
382 template<typename T> double NPTi<T>::getConservedQuantity(void){
383
384 double conservedQuantity;
385 double tb2;
386 double eta2;
387 double E_NPT;
388 double U;
389 double TS;
390 double PV;
391 double extra;
392
393 U = tStats->getTotalE();
394
395 TS = fkBT *
396 (integralOfChidt + tauThermostat * tauThermostat * chi * chi / 2.0) / eConvert;
397
398 PV = (targetPressure * tStats->getVolume() / p_convert) / eConvert;
399
400 tb2 = tauBarostat * tauBarostat;
401 eta2 = eta * eta;
402
403
404 extra = ((double)info->ndfTrans * kB * targetTemp * tb2 * eta2 / 2.0) / eConvert;
405
406 cout.width(8);
407 cout.precision(8);
408
409
410 cout << info->getTime() << "\t"
411 << chi << "\t"
412 << eta << "\t"
413 << U << "\t"
414 << TS << "\t"
415 << PV << "\t"
416 << extra << "\t"
417 << U+TS+PV+extra << endl;
418
419 conservedQuantity = U+TS+PV+extra;
420 return conservedQuantity;
421 }