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root/group/trunk/OOPSE/libmdtools/ExtendedSystem.cpp
Revision: 483
Committed: Wed Apr 9 04:06:43 2003 UTC (21 years, 3 months ago) by gezelter
File size: 8792 byte(s)
Log Message:
fixes for NPT and NVT

File Contents

# Content
1 #include <math.h>
2 #include "Atom.hpp"
3 #include "Molecule.hpp"
4 #include "SimInfo.hpp"
5 #include "Thermo.hpp"
6 #include "ExtendedSystem.hpp"
7 #include "simError.h"
8
9 ExtendedSystem::ExtendedSystem( SimInfo* the_entry_plug ) {
10
11 // get what information we need from the SimInfo object
12
13 entry_plug = the_entry_plug;
14 zeta = 0.0;
15 epsilonDot = 0.0;
16 have_tau_thermostat = 0;
17 have_tau_barostat = 0;
18 have_target_temp = 0;
19 have_target_pressure = 0;
20 have_qmass = 0;
21
22 }
23
24 void ExtendedSystem::NoseHooverNVT( double dt, double ke ){
25
26 // Basic thermostating via Hoover, Phys.Rev.A, 1985, Vol. 31 (5) 1695-1697
27
28 int i;
29 double NkBT, zetaScale, ke_temp;
30 double vx, vy, vz, jx, jy, jz;
31 const double kB = 8.31451e-7; // boltzmann constant in amu*Ang^2*fs^-2/K
32 const double e_convert = 4.184e-4; // to convert ke from kcal/mol to
33 // amu*Ang^2*fs^-2/K
34 DirectionalAtom* dAtom;
35
36 if (this->NVTready()) {
37
38 atoms = entry_plug->atoms;
39
40 ke_temp = ke * e_convert;
41 NkBT = (double)entry_plug->ndf * kB * targetTemp;
42
43 // advance the zeta term to zeta(t + dt) - zeta is 0.0d0 on config. readin
44 // qmass is set in the parameter file
45
46 zeta += dt * ( (ke_temp*2.0 - NkBT) / qmass );
47
48 zetaScale = zeta * dt;
49
50 std::cerr << "zetaScale = " << zetaScale << "\n";
51
52 // perform thermostat scaling on linear velocities and angular momentum
53 for(i = 0; i < entry_plug->n_atoms; i++){
54
55 vx = atoms[i]->get_vx();
56 vy = atoms[i]->get_vy();
57 vz = atoms[i]->get_vz();
58
59 atoms[i]->set_vx(vx * (1.0 - zetaScale));
60 atoms[i]->set_vy(vy * (1.0 - zetaScale));
61 atoms[i]->set_vz(vz * (1.0 - zetaScale));
62 }
63 if( entry_plug->n_oriented ){
64
65 for( i=0; i < entry_plug->n_atoms; i++ ){
66
67 if( atoms[i]->isDirectional() ){
68
69 dAtom = (DirectionalAtom *)atoms[i];
70
71 jx = dAtom->getJx();
72 jy = dAtom->getJy();
73 jz = dAtom->getJz();
74
75 dAtom->setJx(jx * (1.0 - zetaScale));
76 dAtom->setJy(jy * (1.0 - zetaScale));
77 dAtom->setJz(jz * (1.0 - zetaScale));
78 }
79 }
80 }
81 }
82 }
83
84
85 void ExtendedSystem::NoseHooverAndersonNPT( double dt,
86 double ke,
87 double p_tensor[9] ) {
88
89 // Basic barostating via Hoover, Phys.Rev.A, 1985, Vol. 31 (5) 1695-1697
90 // Hoover, Phys.Rev.A, 1986, Vol.34 (3) 2499-2500
91
92 double oldBox[3];
93 double newBox[3];
94 const double kB = 8.31451e-7; // boltzmann constant in amu*Ang^2*fs^-2/K
95 const double p_units = 6.10192996e-9; // converts atm to amu*fs^-2*Ang^-1
96 const double e_convert = 4.184e-4; // to convert ke from kcal/mol to
97 // amu*Ang^2*fs^-2/K
98
99 int i;
100 double p_ext, zetaScale, epsilonScale, scale, NkBT, ke_temp;
101 double volume, p_mol;
102 double vx, vy, vz, jx, jy, jz;
103 DirectionalAtom* dAtom;
104
105 if (this->NPTready()) {
106 atoms = entry_plug->atoms;
107
108 p_ext = targetPressure * p_units;
109 p_mol = (p_tensor[0] + p_tensor[4] + p_tensor[8])/3.0;
110
111 entry_plug->getBox(oldBox);
112 volume = oldBox[0]*oldBox[1]*oldBox[2];
113
114 ke_temp = ke * e_convert;
115 NkBT = (double)entry_plug->ndf * kB * targetTemp;
116
117 // propagate the strain rate
118
119 epsilonDot += dt * ((p_mol - p_ext) * volume /
120 (tauBarostat*tauBarostat * kB * targetTemp) );
121
122 // determine the change in cell volume
123 scale = pow( (1.0 + dt * 3.0 * epsilonDot), (1.0 / 3.0));
124 std::cerr << "pmol = " << p_mol << " p_ext = " << p_ext << " scale = " << scale << "\n";
125
126 newBox[0] = oldBox[0] * scale;
127 newBox[1] = oldBox[1] * scale;
128 newBox[2] = oldBox[2] * scale;
129 volume = newBox[0]*newBox[1]*newBox[2];
130
131 entry_plug->setBox(newBox);
132
133 // perform affine transform to update positions with volume fluctuations
134 this->AffineTransform( oldBox, newBox );
135
136 epsilonScale = epsilonDot * dt;
137
138 // advance the zeta term to zeta(t + dt) - zeta is 0.0d0 on config. readin
139 // qmass is set in the parameter file
140
141 zeta += dt * ( (ke_temp*2.0 - NkBT) / qmass );
142 zetaScale = zeta * dt;
143
144 std::cerr << "zetaScale = " << zetaScale << " epsilonScale = " << epsilonScale << "\n";
145
146 // apply barostating and thermostating to velocities and angular momenta
147 for(i = 0; i < entry_plug->n_atoms; i++){
148
149 vx = atoms[i]->get_vx();
150 vy = atoms[i]->get_vy();
151 vz = atoms[i]->get_vz();
152
153 atoms[i]->set_vx(vx * (1.0 - zetaScale - epsilonScale));
154 atoms[i]->set_vy(vy * (1.0 - zetaScale - epsilonScale));
155 atoms[i]->set_vz(vz * (1.0 - zetaScale - epsilonScale));
156 }
157 if( entry_plug->n_oriented ){
158
159 for( i=0; i < entry_plug->n_atoms; i++ ){
160
161 if( atoms[i]->isDirectional() ){
162
163 dAtom = (DirectionalAtom *)atoms[i];
164
165 jx = dAtom->getJx();
166 jy = dAtom->getJy();
167 jz = dAtom->getJz();
168
169 dAtom->setJx( jx * (1.0 - zetaScale));
170 dAtom->setJy( jy * (1.0 - zetaScale));
171 dAtom->setJz( jz * (1.0 - zetaScale));
172 }
173 }
174 }
175 }
176 }
177
178 void ExtendedSystem::AffineTransform( double oldBox[3], double newBox[3] ){
179
180 int i;
181 double r[3];
182 double boxNum[3];
183 double percentScale[3];
184 double delta[3];
185 double rxi, ryi, rzi;
186
187 molecules = entry_plug->molecules;
188
189 // first determine the scaling factor from the box size change
190 percentScale[0] = (newBox[0] - oldBox[0]) / oldBox[0];
191 percentScale[1] = (newBox[1] - oldBox[1]) / oldBox[1];
192 percentScale[2] = (newBox[2] - oldBox[2]) / oldBox[2];
193
194 for (i=0; i < entry_plug->n_mol; i++) {
195
196 molecules[i].getCOM(r);
197
198 // find the minimum image coordinates of the molecular centers of mass:
199
200 boxNum[0] = oldBox[0] * copysign(1.0,r[0]) *
201 (double)(int)(fabs(r[0]/oldBox[0]) + 0.5);
202
203 boxNum[1] = oldBox[1] * copysign(1.0,r[1]) *
204 (double)(int)(fabs(r[1]/oldBox[1]) + 0.5);
205
206 boxNum[2] = oldBox[2] * copysign(1.0,r[2]) *
207 (double)(int)(fabs(r[2]/oldBox[2]) + 0.5);
208
209 rxi = r[0] - boxNum[0];
210 ryi = r[1] - boxNum[1];
211 rzi = r[2] - boxNum[2];
212
213 // update the minimum image coordinates using the scaling factor
214 rxi += rxi*percentScale[0];
215 ryi += ryi*percentScale[1];
216 rzi += rzi*percentScale[2];
217
218 delta[0] = r[0] - (rxi + boxNum[0]);
219 delta[1] = r[1] - (ryi + boxNum[1]);
220 delta[2] = r[2] - (rzi + boxNum[2]);
221
222 molecules[i].moveCOM(delta);
223 }
224 }
225
226 short int ExtendedSystem::NVTready() {
227 const double kB = 8.31451e-7; // boltzmann constant in amu*Ang^2*fs^-2/K
228 double NkBT;
229
230 if (!have_target_temp) {
231 sprintf( painCave.errMsg,
232 "ExtendedSystem error: You can't use NVT without a targetTemp!\n"
233 );
234 painCave.isFatal = 1;
235 simError();
236 return -1;
237 }
238
239 if (!have_qmass) {
240 if (have_tau_thermostat) {
241
242 NkBT = (double)entry_plug->ndf * kB * targetTemp;
243 std::cerr << "Setting qMass = " << tauThermostat * NkBT << "\n";
244 this->setQmass(tauThermostat * NkBT);
245
246 } else {
247 sprintf( painCave.errMsg,
248 "ExtendedSystem error: If you use the constant temperature\n"
249 " ensemble, you must set either tauThermostat or qMass.\n");
250 painCave.isFatal = 1;
251 simError();
252 }
253 }
254
255 return 1;
256 }
257
258 short int ExtendedSystem::NPTready() {
259 const double kB = 8.31451e-7; // boltzmann constant in amu*Ang^2*fs^-2/K
260 double NkBT;
261
262 if (!have_target_temp) {
263 sprintf( painCave.errMsg,
264 "ExtendedSystem error: You can't use NPT without a targetTemp!\n"
265 );
266 painCave.isFatal = 1;
267 simError();
268 return -1;
269 }
270
271 if (!have_target_pressure) {
272 sprintf( painCave.errMsg,
273 "ExtendedSystem error: You can't use NPT without a targetPressure!\n"
274 );
275 painCave.isFatal = 1;
276 simError();
277 return -1;
278 }
279
280 if (!have_tau_barostat) {
281 sprintf( painCave.errMsg,
282 "ExtendedSystem error: If you use the NPT\n"
283 " ensemble, you must set tauBarostat.\n");
284 painCave.isFatal = 1;
285 simError();
286 }
287
288 if (!have_qmass) {
289 if (have_tau_thermostat) {
290
291 NkBT = (double)entry_plug->ndf * kB * targetTemp;
292 std::cerr << "Setting qMass = " << tauThermostat * NkBT << "\n";
293 this->setQmass(tauThermostat * NkBT);
294
295 } else {
296 sprintf( painCave.errMsg,
297 "ExtendedSystem error: If you use the NPT\n"
298 " ensemble, you must set either tauThermostat or qMass.\n");
299 painCave.isFatal = 1;
300 simError();
301 }
302 }
303 return 1;
304 }
305