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root/group/trunk/OOPSE/libmdtools/NVT.cpp
Revision: 768
Committed: Wed Sep 17 14:22:15 2003 UTC (20 years, 9 months ago) by mmeineke
File size: 6090 byte(s)
Log Message:
fixed NPTi to now work with constraints.

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 thermostating via Hoover, Phys.Rev.A, 1985, Vol. 31 (5) 1695-1697
13
14 template<typename T> NVT<T>::NVT ( SimInfo *theInfo, ForceFields* the_ff):
15 T( theInfo, the_ff )
16 {
17 chi = 0.0;
18 have_tau_thermostat = 0;
19 have_target_temp = 0;
20 have_chi_tolerance = 0;
21 integralOfChidt = 0.0;
22
23 oldVel = new double[3*nAtoms];
24 oldJi = new double[3*nAtoms];
25 }
26
27 template<typename T> NVT<T>::~NVT() {
28 delete[] oldVel;
29 delete[] oldJi;
30 }
31
32 template<typename T> void NVT<T>::moveA() {
33
34 int i, j;
35 DirectionalAtom* dAtom;
36 double Tb[3], ji[3];
37 double A[3][3], I[3][3];
38 double angle, mass;
39 double vel[3], pos[3], frc[3];
40
41 double instTemp;
42
43 // We need the temperature at time = t for the chi update below:
44
45 instTemp = tStats->getTemperature();
46
47 for( i=0; i<nAtoms; i++ ){
48
49 atoms[i]->getVel( vel );
50 atoms[i]->getPos( pos );
51 atoms[i]->getFrc( frc );
52
53 mass = atoms[i]->getMass();
54
55 for (j=0; j < 3; j++) {
56 // velocity half step (use chi from previous step here):
57 vel[j] += dt2 * ((frc[j] / mass ) * eConvert - vel[j]*chi);
58 // position whole step
59 pos[j] += dt * vel[j];
60 }
61
62 atoms[i]->setVel( vel );
63 atoms[i]->setPos( pos );
64
65 if( atoms[i]->isDirectional() ){
66
67 dAtom = (DirectionalAtom *)atoms[i];
68
69 // get and convert the torque to body frame
70
71 dAtom->getTrq( Tb );
72 dAtom->lab2Body( Tb );
73
74 // get the angular momentum, and propagate a half step
75
76 dAtom->getJ( ji );
77
78 for (j=0; j < 3; j++)
79 ji[j] += dt2 * (Tb[j] * eConvert - ji[j]*chi);
80
81 // use the angular velocities to propagate the rotation matrix a
82 // full time step
83
84 dAtom->getA(A);
85 dAtom->getI(I);
86
87 // rotate about the x-axis
88 angle = dt2 * ji[0] / I[0][0];
89 this->rotate( 1, 2, angle, ji, A );
90
91 // rotate about the y-axis
92 angle = dt2 * ji[1] / I[1][1];
93 this->rotate( 2, 0, angle, ji, A );
94
95 // rotate about the z-axis
96 angle = dt * ji[2] / I[2][2];
97 this->rotate( 0, 1, angle, ji, A);
98
99 // rotate about the y-axis
100 angle = dt2 * ji[1] / I[1][1];
101 this->rotate( 2, 0, angle, ji, A );
102
103 // rotate about the x-axis
104 angle = dt2 * ji[0] / I[0][0];
105 this->rotate( 1, 2, angle, ji, A );
106
107 dAtom->setJ( ji );
108 dAtom->setA( A );
109 }
110 }
111
112 if (nConstrained){
113 constrainA();
114 }
115
116 // Finally, evolve chi a half step (just like a velocity) using
117 // temperature at time t, not time t+dt/2
118
119 chi += dt2 * ( instTemp / targetTemp - 1.0) / (tauThermostat*tauThermostat);
120 integralOfChidt += chi*dt2;
121
122 }
123
124 template<typename T> void NVT<T>::moveB( void ){
125 int i, j, k;
126 DirectionalAtom* dAtom;
127 double Tb[3], ji[3];
128 double vel[3], frc[3];
129 double mass;
130 double instTemp;
131 double oldChi, prevChi;
132
133 // Set things up for the iteration:
134
135 oldChi = chi;
136
137 for( i=0; i<nAtoms; i++ ){
138
139 atoms[i]->getVel( vel );
140
141 for (j=0; j < 3; j++)
142 oldVel[3*i + j] = vel[j];
143
144 if( atoms[i]->isDirectional() ){
145
146 dAtom = (DirectionalAtom *)atoms[i];
147
148 dAtom->getJ( ji );
149
150 for (j=0; j < 3; j++)
151 oldJi[3*i + j] = ji[j];
152
153 }
154 }
155
156 // do the iteration:
157
158 for (k=0; k < 4; k++) {
159
160 instTemp = tStats->getTemperature();
161
162 // evolve chi another half step using the temperature at t + dt/2
163
164 prevChi = chi;
165 chi = oldChi + dt2 * ( instTemp / targetTemp - 1.0) /
166 (tauThermostat*tauThermostat);
167
168 for( i=0; i<nAtoms; i++ ){
169
170 atoms[i]->getFrc( frc );
171 atoms[i]->getVel(vel);
172
173 mass = atoms[i]->getMass();
174
175 // velocity half step
176 for (j=0; j < 3; j++)
177 vel[j] = oldVel[3*i+j] + dt2 * ((frc[j] / mass ) * eConvert - oldVel[3*i + j]*chi);
178
179 atoms[i]->setVel( vel );
180
181 if( atoms[i]->isDirectional() ){
182
183 dAtom = (DirectionalAtom *)atoms[i];
184
185 // get and convert the torque to body frame
186
187 dAtom->getTrq( Tb );
188 dAtom->lab2Body( Tb );
189
190 for (j=0; j < 3; j++)
191 ji[j] = oldJi[3*i + j] + dt2 * (Tb[j] * eConvert - oldJi[3*i+j]*chi);
192
193 dAtom->setJ( ji );
194 }
195 }
196
197 if (nConstrained){
198 constrainB();
199 }
200
201 if (fabs(prevChi - chi) <= chiTolerance) break;
202 }
203
204 integralOfChidt += dt2*chi;
205 }
206
207 template<typename T> void NVT<T>::resetIntegrator( void ){
208
209 chi = 0.0;
210 integralOfChidt = 0.0;
211 }
212
213 template<typename T> int NVT<T>::readyCheck() {
214
215 //check parent's readyCheck() first
216 if (T::readyCheck() == -1)
217 return -1;
218
219 // First check to see if we have a target temperature.
220 // Not having one is fatal.
221
222 if (!have_target_temp) {
223 sprintf( painCave.errMsg,
224 "NVT error: You can't use the NVT integrator without a targetTemp!\n"
225 );
226 painCave.isFatal = 1;
227 simError();
228 return -1;
229 }
230
231 // We must set tauThermostat.
232
233 if (!have_tau_thermostat) {
234 sprintf( painCave.errMsg,
235 "NVT error: If you use the constant temperature\n"
236 " integrator, you must set tauThermostat.\n");
237 painCave.isFatal = 1;
238 simError();
239 return -1;
240 }
241
242 if (!have_chi_tolerance) {
243 sprintf( painCave.errMsg,
244 "NVT warning: setting chi tolerance to 1e-6\n");
245 chiTolerance = 1e-6;
246 have_chi_tolerance = 1;
247 painCave.isFatal = 0;
248 simError();
249 }
250
251 return 1;
252
253 }
254
255 template<typename T> double NVT<T>::getConservedQuantity(void){
256
257 double conservedQuantity;
258 double E_NVT;
259
260 //HNVE
261 conservedQuantity = tStats->getTotalE();
262 //HNVE
263
264 E_NVT = (info->getNDF() * kB * targetTemp *
265 (integralOfChidt + tauThermostat * tauThermostat * chi * chi / 2.0 )) / eConvert;
266
267 conservedQuantity += E_NVT;
268
269 //cerr << info->getTime() << "\t" << chi << "\t" << integralOfChidt << "\t" << E_NVT << endl;
270
271 return conservedQuantity;
272 }