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root/group/trunk/OOPSE/libmdtools/NPTf.cpp
Revision: 586
Committed: Wed Jul 9 22:14:06 2003 UTC (21 years ago) by mmeineke
File size: 9436 byte(s)
Log Message:
Bug fixing NPTi and NPTf. there is some error in the caclulation of HmatInverse.

File Contents

# Content
1 #include "Atom.hpp"
2 #include "SRI.hpp"
3 #include "AbstractClasses.hpp"
4 #include "SimInfo.hpp"
5 #include "ForceFields.hpp"
6 #include "Thermo.hpp"
7 #include "ReadWrite.hpp"
8 #include "Integrator.hpp"
9 #include "simError.h"
10
11
12 // Basic non-isotropic thermostating and barostating via the Melchionna
13 // modification of the Hoover algorithm:
14 //
15 // Melchionna, S., Ciccotti, G., and Holian, B. L., 1993,
16 // Molec. Phys., 78, 533.
17 //
18 // and
19 //
20 // Hoover, W. G., 1986, Phys. Rev. A, 34, 2499.
21
22 NPTf::NPTf ( SimInfo *theInfo, ForceFields* the_ff):
23 Integrator( theInfo, the_ff )
24 {
25 int i;
26 chi = 0.0;
27 for(i = 0; i < 9; i++) eta[i] = 0.0;
28 have_tau_thermostat = 0;
29 have_tau_barostat = 0;
30 have_target_temp = 0;
31 have_target_pressure = 0;
32 }
33
34 void NPTf::moveA() {
35
36 int i,j,k;
37 int atomIndex, aMatIndex;
38 DirectionalAtom* dAtom;
39 double Tb[3];
40 double ji[3];
41 double rj[3];
42 double ident[3][3], eta1[3][3], eta2[3][3], hmnew[3][3];
43 double hm[9];
44 double vx, vy, vz;
45 double scx, scy, scz;
46 double instaTemp, instaPress, instaVol;
47 double tt2, tb2;
48 double angle;
49 double press[9];
50
51 tt2 = tauThermostat * tauThermostat;
52 tb2 = tauBarostat * tauBarostat;
53
54 instaTemp = tStats->getTemperature();
55 tStats->getPressureTensor(press);
56 instaVol = tStats->getVolume();
57
58 // first evolve chi a half step
59
60 chi += dt2 * ( instaTemp / targetTemp - 1.0) / tt2;
61
62 eta[0] += dt2 * instaVol * (press[0] - targetPressure/p_convert) /
63 (NkBT*tb2);
64 eta[1] += dt2 * instaVol * press[1] / (NkBT*tb2);
65 eta[2] += dt2 * instaVol * press[2] / (NkBT*tb2);
66 eta[3] += dt2 * instaVol * press[3] / (NkBT*tb2);
67 eta[4] += dt2 * instaVol * (press[4] - targetPressure/p_convert) /
68 (NkBT*tb2);
69 eta[5] += dt2 * instaVol * press[5] / (NkBT*tb2);
70 eta[6] += dt2 * instaVol * press[6] / (NkBT*tb2);
71 eta[7] += dt2 * instaVol * press[7] / (NkBT*tb2);
72 eta[8] += dt2 * instaVol * (press[8] - targetPressure/p_convert) /
73 (NkBT*tb2);
74
75 for( i=0; i<nAtoms; i++ ){
76 atomIndex = i * 3;
77 aMatIndex = i * 9;
78
79 // velocity half step
80
81 vx = vel[atomIndex];
82 vy = vel[atomIndex+1];
83 vz = vel[atomIndex+2];
84
85 scx = (chi + eta[0])*vx + eta[1]*vy + eta[2]*vz;
86 scy = eta[3]*vx + (chi + eta[4])*vy + eta[5]*vz;
87 scz = eta[6]*vx + eta[7]*vy + (chi + eta[8])*vz;
88
89 vx += dt2 * ((frc[atomIndex] /atoms[i]->getMass())*eConvert - scx);
90 vy += dt2 * ((frc[atomIndex+1]/atoms[i]->getMass())*eConvert - scy);
91 vz += dt2 * ((frc[atomIndex+2]/atoms[i]->getMass())*eConvert - scz);
92
93 vel[atomIndex] = vx;
94 vel[atomIndex+1] = vy;
95 vel[atomIndex+2] = vz;
96
97 // position whole step
98
99 rj[0] = pos[atomIndex];
100 rj[1] = pos[atomIndex+1];
101 rj[2] = pos[atomIndex+2];
102
103 info->wrapVector(rj);
104
105 scx = eta[0]*rj[0] + eta[1]*rj[1] + eta[2]*rj[2];
106 scy = eta[3]*rj[0] + eta[4]*rj[1] + eta[5]*rj[2];
107 scz = eta[6]*rj[0] + eta[7]*rj[1] + eta[8]*rj[2];
108
109 pos[atomIndex] += dt * (vel[atomIndex] + scx);
110 pos[atomIndex+1] += dt * (vel[atomIndex+1] + scy);
111 pos[atomIndex+2] += dt * (vel[atomIndex+2] + scz);
112
113 if( atoms[i]->isDirectional() ){
114
115 dAtom = (DirectionalAtom *)atoms[i];
116
117 // get and convert the torque to body frame
118
119 Tb[0] = dAtom->getTx();
120 Tb[1] = dAtom->getTy();
121 Tb[2] = dAtom->getTz();
122
123 dAtom->lab2Body( Tb );
124
125 // get the angular momentum, and propagate a half step
126
127 ji[0] = dAtom->getJx();
128 ji[1] = dAtom->getJy();
129 ji[2] = dAtom->getJz();
130
131 ji[0] += dt2 * (Tb[0] * eConvert - ji[0]*chi);
132 ji[1] += dt2 * (Tb[1] * eConvert - ji[1]*chi);
133 ji[2] += dt2 * (Tb[2] * eConvert - ji[2]*chi);
134
135 // use the angular velocities to propagate the rotation matrix a
136 // full time step
137
138 // rotate about the x-axis
139 angle = dt2 * ji[0] / dAtom->getIxx();
140 this->rotate( 1, 2, angle, ji, &Amat[aMatIndex] );
141
142 // rotate about the y-axis
143 angle = dt2 * ji[1] / dAtom->getIyy();
144 this->rotate( 2, 0, angle, ji, &Amat[aMatIndex] );
145
146 // rotate about the z-axis
147 angle = dt * ji[2] / dAtom->getIzz();
148 this->rotate( 0, 1, angle, ji, &Amat[aMatIndex] );
149
150 // rotate about the y-axis
151 angle = dt2 * ji[1] / dAtom->getIyy();
152 this->rotate( 2, 0, angle, ji, &Amat[aMatIndex] );
153
154 // rotate about the x-axis
155 angle = dt2 * ji[0] / dAtom->getIxx();
156 this->rotate( 1, 2, angle, ji, &Amat[aMatIndex] );
157
158 dAtom->setJx( ji[0] );
159 dAtom->setJy( ji[1] );
160 dAtom->setJz( ji[2] );
161 }
162
163 }
164
165 // Scale the box after all the positions have been moved:
166
167 // Use a taylor expansion for eta products: Hmat = Hmat . exp(dt * etaMat)
168 // Hmat = Hmat . ( Ident + dt * etaMat + dt^2 * etaMat*etaMat / 2)
169
170
171 for(i=0; i<3; i++){
172 for(j=0; j<3; j++){
173 ident[i][j] = 0.0;
174 eta1[i][j] = eta[3*i+j];
175 eta2[i][j] = 0.0;
176 for(k=0; k<3; k++){
177 eta2[i][j] += eta[3*i+k] * eta[3*k+j];
178 }
179 }
180 ident[i][i] = 1.0;
181 }
182
183
184 info->getBoxM(hm);
185
186 for(i=0; i<3; i++){
187 for(j=0; j<3; j++){
188 hmnew[i][j] = 0.0;
189 for(k=0; k<3; k++){
190 // remember that hmat has transpose ordering for Fortran compat:
191 hmnew[i][j] += hm[3*k+i] * (ident[k][j]
192 + dt * eta1[k][j]
193 + 0.5 * dt * dt * eta2[k][j]);
194 }
195 }
196 }
197
198 for (i = 0; i < 3; i++) {
199 for (j = 0; j < 3; j++) {
200 // remember that hmat has transpose ordering for Fortran compat:
201 hm[3*j + i] = hmnew[i][j];
202 }
203 }
204
205 info->setBoxM(hm);
206
207 }
208
209 void NPTf::moveB( void ){
210 int i,j,k;
211 int atomIndex;
212 DirectionalAtom* dAtom;
213 double Tb[3];
214 double ji[3];
215 double press[9];
216 double instaTemp, instaVol;
217 double tt2, tb2;
218 double vx, vy, vz;
219 double scx, scy, scz;
220 const double p_convert = 1.63882576e8;
221
222 tt2 = tauThermostat * tauThermostat;
223 tb2 = tauBarostat * tauBarostat;
224
225 instaTemp = tStats->getTemperature();
226 tStats->getPressureTensor(press);
227 instaVol = tStats->getVolume();
228
229 // first evolve chi a half step
230
231 chi += dt2 * ( instaTemp / targetTemp - 1.0) / tt2;
232
233 eta[0] += dt2 * instaVol * (press[0] - targetPressure/p_convert) /
234 (NkBT*tb2);
235 eta[1] += dt2 * instaVol * press[1] / (NkBT*tb2);
236 eta[2] += dt2 * instaVol * press[2] / (NkBT*tb2);
237 eta[3] += dt2 * instaVol * press[3] / (NkBT*tb2);
238 eta[4] += dt2 * instaVol * (press[4] - targetPressure/p_convert) /
239 (NkBT*tb2);
240 eta[5] += dt2 * instaVol * press[5] / (NkBT*tb2);
241 eta[6] += dt2 * instaVol * press[6] / (NkBT*tb2);
242 eta[7] += dt2 * instaVol * press[7] / (NkBT*tb2);
243 eta[8] += dt2 * instaVol * (press[8] - targetPressure/p_convert) /
244 (NkBT*tb2);
245
246 for( i=0; i<nAtoms; i++ ){
247 atomIndex = i * 3;
248
249 // velocity half step
250
251 vx = vel[atomIndex];
252 vy = vel[atomIndex+1];
253 vz = vel[atomIndex+2];
254
255 scx = (chi + eta[0])*vx + eta[1]*vy + eta[2]*vz;
256 scy = eta[3]*vx + (chi + eta[4])*vy + eta[5]*vz;
257 scz = eta[6]*vx + eta[7]*vy + (chi + eta[8])*vz;
258
259 vx += dt2 * ((frc[atomIndex] /atoms[i]->getMass())*eConvert - scx);
260 vy += dt2 * ((frc[atomIndex+1]/atoms[i]->getMass())*eConvert - scy);
261 vz += dt2 * ((frc[atomIndex+2]/atoms[i]->getMass())*eConvert - scz);
262
263 vel[atomIndex] = vx;
264 vel[atomIndex+1] = vy;
265 vel[atomIndex+2] = vz;
266
267 if( atoms[i]->isDirectional() ){
268
269 dAtom = (DirectionalAtom *)atoms[i];
270
271 // get and convert the torque to body frame
272
273 Tb[0] = dAtom->getTx();
274 Tb[1] = dAtom->getTy();
275 Tb[2] = dAtom->getTz();
276
277 dAtom->lab2Body( Tb );
278
279 // get the angular momentum, and complete the angular momentum
280 // half step
281
282 ji[0] = dAtom->getJx();
283 ji[1] = dAtom->getJy();
284 ji[2] = dAtom->getJz();
285
286 ji[0] += dt2 * (Tb[0] * eConvert - ji[0]*chi);
287 ji[1] += dt2 * (Tb[1] * eConvert - ji[1]*chi);
288 ji[2] += dt2 * (Tb[2] * eConvert - ji[2]*chi);
289
290 dAtom->setJx( ji[0] );
291 dAtom->setJy( ji[1] );
292 dAtom->setJz( ji[2] );
293 }
294 }
295 }
296
297 int NPTf::readyCheck() {
298
299 // First check to see if we have a target temperature.
300 // Not having one is fatal.
301
302 if (!have_target_temp) {
303 sprintf( painCave.errMsg,
304 "NPTf error: You can't use the NPTf integrator\n"
305 " without a targetTemp!\n"
306 );
307 painCave.isFatal = 1;
308 simError();
309 return -1;
310 }
311
312 if (!have_target_pressure) {
313 sprintf( painCave.errMsg,
314 "NPTf error: You can't use the NPTf integrator\n"
315 " without a targetPressure!\n"
316 );
317 painCave.isFatal = 1;
318 simError();
319 return -1;
320 }
321
322 // We must set tauThermostat.
323
324 if (!have_tau_thermostat) {
325 sprintf( painCave.errMsg,
326 "NPTf error: If you use the NPTf\n"
327 " integrator, you must set tauThermostat.\n");
328 painCave.isFatal = 1;
329 simError();
330 return -1;
331 }
332
333 // We must set tauBarostat.
334
335 if (!have_tau_barostat) {
336 sprintf( painCave.errMsg,
337 "NPTf error: If you use the NPTf\n"
338 " integrator, you must set tauBarostat.\n");
339 painCave.isFatal = 1;
340 simError();
341 return -1;
342 }
343
344 // We need NkBT a lot, so just set it here:
345
346 NkBT = (double)info->ndf * kB * targetTemp;
347
348 return 1;
349 }