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root/group/trunk/OOPSE/libmdtools/NPTfm.cpp
Revision: 658
Committed: Thu Jul 31 15:35:07 2003 UTC (20 years, 11 months ago) by tim
File size: 9899 byte(s)
Log Message:
 Added Z constraint.

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