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root/group/trunk/OOPSE/libmdtools/ExtendedSystem.cpp
Revision: 481
Committed: Tue Apr 8 21:35:49 2003 UTC (21 years, 3 months ago) by gezelter
File size: 8663 byte(s)
Log Message:
Fixes for NPT / 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_int ) {
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_int * p_units;
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 // propogate 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
125 newBox[0] = oldBox[0] * scale;
126 newBox[1] = oldBox[1] * scale;
127 newBox[2] = oldBox[2] * scale;
128 volume = newBox[0]*newBox[1]*newBox[2];
129
130 entry_plug->setBox(newBox);
131
132 // perform affine transform to update positions with volume fluctuations
133 this->AffineTransform( oldBox, newBox );
134
135 epsilonScale = epsilonDot * dt;
136
137 // advance the zeta term to zeta(t + dt) - zeta is 0.0d0 on config. readin
138 // qmass is set in the parameter file
139
140 zeta += dt * ( (ke_temp*2.0 - NkBT) / qmass );
141 zetaScale = zeta * dt;
142
143 std::cerr << "zetaScale = " << zetaScale << " epsilonScale = " << epsilonScale << "\n";
144
145 // apply barostating and thermostating to velocities and angular momenta
146 for(i = 0; i < entry_plug->n_atoms; i++){
147
148 vx = atoms[i]->get_vx();
149 vy = atoms[i]->get_vy();
150 vz = atoms[i]->get_vz();
151
152 atoms[i]->set_vx(vx * (1.0 - zetaScale - epsilonScale));
153 atoms[i]->set_vy(vy * (1.0 - zetaScale - epsilonScale));
154 atoms[i]->set_vz(vz * (1.0 - zetaScale - epsilonScale));
155 }
156 if( entry_plug->n_oriented ){
157
158 for( i=0; i < entry_plug->n_atoms; i++ ){
159
160 if( atoms[i]->isDirectional() ){
161
162 dAtom = (DirectionalAtom *)atoms[i];
163
164 jx = dAtom->getJx();
165 jy = dAtom->getJy();
166 jz = dAtom->getJz();
167
168 dAtom->setJx( jx * (1.0 - zetaScale));
169 dAtom->setJy( jy * (1.0 - zetaScale));
170 dAtom->setJz( jz * (1.0 - zetaScale));
171 }
172 }
173 }
174 }
175 }
176
177 void ExtendedSystem::AffineTransform( double oldBox[3], double newBox[3] ){
178
179 int i;
180 double r[3];
181 double boxNum[3];
182 double percentScale[3];
183 double delta[3];
184 double rxi, ryi, rzi;
185
186 molecules = entry_plug->molecules;
187
188 // first determine the scaling factor from the box size change
189 percentScale[0] = (newBox[0] - oldBox[0]) / oldBox[0];
190 percentScale[1] = (newBox[1] - oldBox[1]) / oldBox[1];
191 percentScale[2] = (newBox[2] - oldBox[2]) / oldBox[2];
192
193 for (i=0; i < entry_plug->n_mol; i++) {
194
195 molecules[i].getCOM(r);
196
197 // find the minimum image coordinates of the molecular centers of mass:
198
199 boxNum[0] = oldBox[0] * copysign(1.0,r[0]) *
200 (double)(int)(fabs(r[0]/oldBox[0]) + 0.5);
201
202 boxNum[1] = oldBox[1] * copysign(1.0,r[1]) *
203 (double)(int)(fabs(r[1]/oldBox[1]) + 0.5);
204
205 boxNum[2] = oldBox[2] * copysign(1.0,r[2]) *
206 (double)(int)(fabs(r[2]/oldBox[2]) + 0.5);
207
208 rxi = r[0] - boxNum[0];
209 ryi = r[1] - boxNum[1];
210 rzi = r[2] - boxNum[2];
211
212 // update the minimum image coordinates using the scaling factor
213 rxi += rxi*percentScale[0];
214 ryi += ryi*percentScale[1];
215 rzi += rzi*percentScale[2];
216
217 delta[0] = r[0] - (rxi + boxNum[0]);
218 delta[1] = r[1] - (ryi + boxNum[1]);
219 delta[2] = r[2] - (rzi + boxNum[2]);
220
221 molecules[i].moveCOM(delta);
222 }
223 }
224
225 short int ExtendedSystem::NVTready() {
226 const double kB = 8.31451e-7; // boltzmann constant in amu*Ang^2*fs^-2/K
227 double NkBT;
228
229 if (!have_target_temp) {
230 sprintf( painCave.errMsg,
231 "ExtendedSystem error: You can't use NVT without a targetTemp!\n"
232 );
233 painCave.isFatal = 1;
234 simError();
235 return -1;
236 }
237
238 if (!have_qmass) {
239 if (have_tau_thermostat) {
240
241 NkBT = (double)entry_plug->ndf * kB * targetTemp;
242 std::cerr << "Setting qMass = " << tauThermostat * NkBT << "\n";
243 this->setQmass(tauThermostat * NkBT);
244
245 } else {
246 sprintf( painCave.errMsg,
247 "ExtendedSystem error: If you use the constant temperature\n"
248 " ensemble, you must set either tauThermostat or qMass.\n");
249 painCave.isFatal = 1;
250 simError();
251 }
252 }
253
254 return 0;
255 }
256
257 short int ExtendedSystem::NPTready() {
258 const double kB = 8.31451e-7; // boltzmann constant in amu*Ang^2*fs^-2/K
259 double NkBT;
260
261 if (!have_target_temp) {
262 sprintf( painCave.errMsg,
263 "ExtendedSystem error: You can't use NPT without a targetTemp!\n"
264 );
265 painCave.isFatal = 1;
266 simError();
267 return -1;
268 }
269
270 if (!have_target_pressure) {
271 sprintf( painCave.errMsg,
272 "ExtendedSystem error: You can't use NPT without a targetPressure!\n"
273 );
274 painCave.isFatal = 1;
275 simError();
276 return -1;
277 }
278
279 if (!have_tau_barostat) {
280 sprintf( painCave.errMsg,
281 "ExtendedSystem error: If you use the NPT\n"
282 " ensemble, you must set tauBarostat.\n");
283 painCave.isFatal = 1;
284 simError();
285 }
286
287 if (!have_qmass) {
288 if (have_tau_thermostat) {
289
290 NkBT = (double)entry_plug->ndf * kB * targetTemp;
291 std::cerr << "Setting qMass = " << tauThermostat * NkBT << "\n";
292 this->setQmass(tauThermostat * NkBT);
293
294 } else {
295 sprintf( painCave.errMsg,
296 "ExtendedSystem error: If you use the NPT\n"
297 " ensemble, you must set either tauThermostat or qMass.\n");
298 painCave.isFatal = 1;
299 simError();
300 }
301 }
302 return 0;
303 }
304