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root/group/trunk/OOPSE/libmdtools/NPTfm.cpp
Revision: 763
Committed: Mon Sep 15 16:52:02 2003 UTC (21 years, 7 months ago) by tim
File size: 10662 byte(s)
Log Message:
add conserved quantity to statWriter
fix bug of vector wrapping at NPTi

File Contents

# Content
1 #include <cmath>
2 #include "Atom.hpp"
3 #include "Molecule.hpp"
4 #include "SRI.hpp"
5 #include "AbstractClasses.hpp"
6 #include "SimInfo.hpp"
7 #include "ForceFields.hpp"
8 #include "Thermo.hpp"
9 #include "ReadWrite.hpp"
10 #include "Integrator.hpp"
11 #include "simError.h"
12
13
14 // Basic non-isotropic thermostating and barostating via the Melchionna
15 // modification of the Hoover algorithm:
16 //
17 // Melchionna, S., Ciccotti, G., and Holian, B. L., 1993,
18 // Molec. Phys., 78, 533.
19 //
20 // and
21 //
22 // Hoover, W. G., 1986, Phys. Rev. A, 34, 2499.
23
24 // The NPTfm variant scales the molecular center-of-mass coordinates
25 // instead of the atomic coordinates
26
27 template<typename T> NPTfm<T>::NPTfm ( SimInfo *theInfo, ForceFields* the_ff):
28 T( theInfo, the_ff )
29 {
30 int i, j;
31 chi = 0.0;
32 integralOfChidt = 0.0;
33
34 for(i = 0; i < 3; i++)
35 for (j = 0; j < 3; j++)
36 eta[i][j] = 0.0;
37
38 have_tau_thermostat = 0;
39 have_tau_barostat = 0;
40 have_target_temp = 0;
41 have_target_pressure = 0;
42 }
43
44 template<typename T> void NPTfm<T>::moveA() {
45
46 int i, j, k;
47 DirectionalAtom* dAtom;
48 double Tb[3], ji[3];
49 double A[3][3], I[3][3];
50 double angle, mass;
51 double vel[3], pos[3], frc[3];
52
53 double rj[3];
54 double instaTemp, instaPress, instaVol;
55 double tt2, tb2;
56 double sc[3];
57 double eta2ij, smallScale, bigScale, offDiagMax;
58 double press[3][3], vScale[3][3], hm[3][3], hmnew[3][3], scaleMat[3][3];
59
60 int nInMol;
61 double rc[3];
62
63 nMols = info->n_mol;
64 myMolecules = info->molecules;
65
66 tt2 = tauThermostat * tauThermostat;
67 tb2 = tauBarostat * tauBarostat;
68
69 instaTemp = tStats->getTemperature();
70 tStats->getPressureTensor(press);
71 instaVol = tStats->getVolume();
72
73 // first evolve chi a half step
74
75 chi += dt2 * ( instaTemp / targetTemp - 1.0) / tt2;
76
77 for (i = 0; i < 3; i++ ) {
78 for (j = 0; j < 3; j++ ) {
79 if (i == j) {
80
81 eta[i][j] += dt2 * instaVol *
82 (press[i][j] - targetPressure/p_convert) / (NkBT*tb2);
83
84 vScale[i][j] = eta[i][j] + chi;
85
86 } else {
87
88 eta[i][j] += dt2 * instaVol * press[i][j] / (NkBT*tb2);
89
90 vScale[i][j] = eta[i][j];
91
92 }
93 }
94 }
95
96
97 for (i = 0; i < nMols; i++) {
98
99 myMolecules[i].getCOM(rc);
100
101 nInMol = myMolecules[i].getNAtoms();
102 myAtoms = myMolecules[i].getMyAtoms();
103
104 // find the minimum image coordinates of the molecular centers of mass:
105
106 info->wrapVector(rc);
107
108 for( j=0; j< nInMol; j++ ){
109
110 if(myAtoms[j] != NULL) {
111
112 myAtoms[j]->getVel( vel );
113 myAtoms[j]->getPos( pos );
114 myAtoms[j]->getFrc( frc );
115
116 mass = myAtoms[j]->getMass();
117
118 // velocity half step
119
120 info->matVecMul3( vScale, vel, sc );
121
122 for (k = 0; k < 3; k++)
123 vel[k] += dt2 * ((frc[k] / mass) * eConvert - sc[k]);
124
125 myAtoms[j]->setVel( vel );
126
127 // position whole step
128
129 info->matVecMul3( eta, rc, sc );
130
131 for (k = 0; k < 3; k++ )
132 pos[k] += dt * (vel[k] + sc[k]);
133
134 myAtoms[j]->setPos( pos );
135
136 if( myAtoms[j]->isDirectional() ){
137
138 dAtom = (DirectionalAtom *)myAtoms[j];
139
140 // get and convert the torque to body frame
141
142 dAtom->getTrq( Tb );
143 dAtom->lab2Body( Tb );
144
145 // get the angular momentum, and propagate a half step
146
147 dAtom->getJ( ji );
148
149 for (k=0; k < 3; k++)
150 ji[k] += dt2 * (Tb[k] * eConvert - ji[k]*chi);
151
152 // use the angular velocities to propagate the rotation matrix a
153 // full time step
154
155 dAtom->getA(A);
156 dAtom->getI(I);
157
158 // rotate about the x-axis
159 angle = dt2 * ji[0] / I[0][0];
160 this->rotate( 1, 2, angle, ji, A );
161
162 // rotate about the y-axis
163 angle = dt2 * ji[1] / I[1][1];
164 this->rotate( 2, 0, angle, ji, A );
165
166 // rotate about the z-axis
167 angle = dt * ji[2] / I[2][2];
168 this->rotate( 0, 1, angle, ji, A);
169
170 // rotate about the y-axis
171 angle = dt2 * ji[1] / I[1][1];
172 this->rotate( 2, 0, angle, ji, A );
173
174 // rotate about the x-axis
175 angle = dt2 * ji[0] / I[0][0];
176 this->rotate( 1, 2, angle, ji, A );
177
178 dAtom->setJ( ji );
179 dAtom->setA( A );
180 }
181 }
182 }
183 }
184
185 // Scale the box after all the positions have been moved:
186
187 // Use a taylor expansion for eta products: Hmat = Hmat . exp(dt * etaMat)
188 // Hmat = Hmat . ( Ident + dt * etaMat + dt^2 * etaMat*etaMat / 2)
189
190
191 bigScale = 1.0;
192 smallScale = 1.0;
193 offDiagMax = 0.0;
194
195 for(i=0; i<3; i++){
196 for(j=0; j<3; j++){
197
198 // Calculate the matrix Product of the eta array (we only need
199 // the ij element right now):
200
201 eta2ij = 0.0;
202 for(k=0; k<3; k++){
203 eta2ij += eta[i][k] * eta[k][j];
204 }
205
206 scaleMat[i][j] = 0.0;
207 // identity matrix (see above):
208 if (i == j) scaleMat[i][j] = 1.0;
209 // Taylor expansion for the exponential truncated at second order:
210 scaleMat[i][j] += dt*eta[i][j] + 0.5*dt*dt*eta2ij;
211
212 if (i != j)
213 if (fabs(scaleMat[i][j]) > offDiagMax)
214 offDiagMax = fabs(scaleMat[i][j]);
215 }
216 if (scaleMat[i][i] > bigScale) bigScale = scaleMat[i][i];
217 if (scaleMat[i][i] < smallScale) smallScale = scaleMat[i][i];
218 }
219
220 if ((bigScale > 1.1) || (smallScale < 0.9)) {
221 sprintf( painCave.errMsg,
222 "NPTf error: Attempting a Box scaling of more than 10 percent.\n"
223 " Check your tauBarostat, as it is probably too small!\n\n"
224 " scaleMat = [%lf\t%lf\t%lf]\n"
225 " [%lf\t%lf\t%lf]\n"
226 " [%lf\t%lf\t%lf]\n",
227 scaleMat[0][0],scaleMat[0][1],scaleMat[0][2],
228 scaleMat[1][0],scaleMat[1][1],scaleMat[1][2],
229 scaleMat[2][0],scaleMat[2][1],scaleMat[2][2]);
230 painCave.isFatal = 1;
231 simError();
232 } else if (offDiagMax > 0.1) {
233 sprintf( painCave.errMsg,
234 "NPTf error: Attempting an off-diagonal Box scaling of more than 10 percent.\n"
235 " Check your tauBarostat, as it is probably too small!\n\n"
236 " scaleMat = [%lf\t%lf\t%lf]\n"
237 " [%lf\t%lf\t%lf]\n"
238 " [%lf\t%lf\t%lf]\n",
239 scaleMat[0][0],scaleMat[0][1],scaleMat[0][2],
240 scaleMat[1][0],scaleMat[1][1],scaleMat[1][2],
241 scaleMat[2][0],scaleMat[2][1],scaleMat[2][2]);
242 painCave.isFatal = 1;
243 simError();
244 } else {
245 info->getBoxM(hm);
246 info->matMul3(hm, scaleMat, hmnew);
247 info->setBoxM(hmnew);
248 }
249 }
250
251 template<typename T> void NPTfm<T>::moveB( void ){
252
253 int i, j;
254 DirectionalAtom* dAtom;
255 double Tb[3], ji[3];
256 double vel[3], frc[3];
257 double mass;
258
259 double instaTemp, instaPress, instaVol;
260 double tt2, tb2;
261 double sc[3];
262 double press[3][3], vScale[3][3];
263
264 tt2 = tauThermostat * tauThermostat;
265 tb2 = tauBarostat * tauBarostat;
266
267 instaTemp = tStats->getTemperature();
268 tStats->getPressureTensor(press);
269 instaVol = tStats->getVolume();
270
271 // first evolve chi a half step
272
273 chi += dt2 * ( instaTemp / targetTemp - 1.0) / tt2;
274
275 for (i = 0; i < 3; i++ ) {
276 for (j = 0; j < 3; j++ ) {
277 if (i == j) {
278
279 eta[i][j] += dt2 * instaVol *
280 (press[i][j] - targetPressure/p_convert) / (NkBT*tb2);
281
282 vScale[i][j] = eta[i][j] + chi;
283
284 } else {
285
286 eta[i][j] += dt2 * instaVol * press[i][j] / (NkBT*tb2);
287
288 vScale[i][j] = eta[i][j];
289
290 }
291 }
292 }
293
294 for( i=0; i<nAtoms; i++ ){
295
296 atoms[i]->getVel( vel );
297 atoms[i]->getFrc( frc );
298
299 mass = atoms[i]->getMass();
300
301 // velocity half step
302
303 info->matVecMul3( vScale, vel, sc );
304
305 for (j = 0; j < 3; j++) {
306 vel[j] += dt2 * ((frc[j] / mass) * eConvert - sc[j]);
307 }
308
309 atoms[i]->setVel( vel );
310
311 if( atoms[i]->isDirectional() ){
312
313 dAtom = (DirectionalAtom *)atoms[i];
314
315 // get and convert the torque to body frame
316
317 dAtom->getTrq( Tb );
318 dAtom->lab2Body( Tb );
319
320 // get the angular momentum, and propagate a half step
321
322 dAtom->getJ( ji );
323
324 for (j=0; j < 3; j++)
325 ji[j] += dt2 * (Tb[j] * eConvert - ji[j]*chi);
326
327 dAtom->setJ( ji );
328
329 }
330 }
331 }
332
333 template<typename T> void NPTfm<T>::resetIntegrator() {
334 int i,j;
335
336 chi = 0.0;
337
338 for(i = 0; i < 3; i++)
339 for (j = 0; j < 3; j++)
340 eta[i][j] = 0.0;
341 }
342
343 template<typename T> int NPTfm<T>::readyCheck() {
344
345 //check parent's readyCheck() first
346 if (T::readyCheck() == -1)
347 return -1;
348
349 // First check to see if we have a target temperature.
350 // Not having one is fatal.
351
352 if (!have_target_temp) {
353 sprintf( painCave.errMsg,
354 "NPTfm error: You can't use the NPTfm integrator\n"
355 " without a targetTemp!\n"
356 );
357 painCave.isFatal = 1;
358 simError();
359 return -1;
360 }
361
362 if (!have_target_pressure) {
363 sprintf( painCave.errMsg,
364 "NPTfm error: You can't use the NPTfm integrator\n"
365 " without a targetPressure!\n"
366 );
367 painCave.isFatal = 1;
368 simError();
369 return -1;
370 }
371
372 // We must set tauThermostat.
373
374 if (!have_tau_thermostat) {
375 sprintf( painCave.errMsg,
376 "NPTfm error: If you use the NPTfm\n"
377 " integrator, you must set tauThermostat.\n");
378 painCave.isFatal = 1;
379 simError();
380 return -1;
381 }
382
383 // We must set tauBarostat.
384
385 if (!have_tau_barostat) {
386 sprintf( painCave.errMsg,
387 "NPTfm error: If you use the NPTfm\n"
388 " integrator, you must set tauBarostat.\n");
389 painCave.isFatal = 1;
390 simError();
391 return -1;
392 }
393
394 // We need NkBT a lot, so just set it here:
395
396 NkBT = (double)info->ndf * kB * targetTemp;
397
398 return 1;
399 }
400
401 template<typename T> double NPTfm<T>::getConservedQuantity(void){
402
403 double conservedQuantity;
404 double tb2;
405 double trEta;
406
407 //HNVE
408 conservedQuantity = tStats->getTotalE();
409
410 //HNVT
411 conservedQuantity += (info->getNDF() * kB * targetTemp *
412 (integralOfChidt + tauThermostat * tauThermostat * chi * chi / 2.0)) / eConvert ;
413
414 //HNPT
415 tb2 = tauBarostat *tauBarostat;
416
417 trEta = info->matTrace3(eta);
418
419 conservedQuantity += (targetPressure * tStats->getVolume() / p_convert +
420 3*NkBT/2 * tb2 * trEta * trEta) / eConvert;
421
422 return conservedQuantity;
423 }