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root/group/trunk/OOPSE/libmdtools/NPTi.cpp
Revision: 575
Committed: Tue Jul 8 21:06:14 2003 UTC (21 years ago) by gezelter
File size: 6279 byte(s)
Log Message:
fixed box scaling

File Contents

# User Rev Content
1 gezelter 574 #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 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     NPTi::NPTi ( SimInfo *theInfo, ForceFields* the_ff):
23     Integrator( theInfo, the_ff )
24     {
25     chi = 0.0;
26     eta = 0.0;
27     have_tau_thermostat = 0;
28     have_tau_barostat = 0;
29     have_target_temp = 0;
30     have_target_pressure = 0;
31     }
32    
33     void NPTi::moveA() {
34    
35     int i,j,k;
36     int atomIndex, aMatIndex;
37     DirectionalAtom* dAtom;
38     double Tb[3];
39     double ji[3];
40     double rj[3];
41     double instaTemp, instaPress, instaVol;
42     double tt2, tb2;
43     double angle;
44    
45     tt2 = tauThermostat * tauThermostat;
46     tb2 = tauBarostat * tauBarostat;
47    
48     instaTemp = tStats->getTemperature();
49     instaPress = tStats->getPressure();
50     instaVol = tStats->getVolume();
51    
52     // first evolve chi a half step
53    
54     chi += dt2 * ( instaTemp / targetTemp - 1.0) / tt2;
55     eta += dt2 * ( instaVol * (instaPress - targetPressure) / (NkBT*tb2));
56    
57     for( i=0; i<nAtoms; i++ ){
58     atomIndex = i * 3;
59     aMatIndex = i * 9;
60    
61     // velocity half step
62     for( j=atomIndex; j<(atomIndex+3); j++ )
63     vel[j] += dt2 * ((frc[j]/atoms[i]->getMass())*eConvert
64     - vel[j]*(chi+eta));
65    
66     // position whole step
67    
68     for( j=atomIndex; j<(atomIndex+3); j=j+3 ) {
69     rj[0] = pos[j];
70     rj[1] = pos[j+1];
71     rj[2] = pos[j+2];
72    
73     info->wrapVector(rj);
74    
75     pos[j] += dt * (vel[j] + eta*rj[0]);
76     pos[j+1] += dt * (vel[j+1] + eta*rj[1]);
77     pos[j+2] += dt * (vel[j+2] + eta*rj[2]);
78     }
79    
80     // Scale the box after all the positions have been moved:
81    
82 gezelter 575 info->scaleBox(exp(dt*eta));
83 gezelter 574
84     if( atoms[i]->isDirectional() ){
85    
86     dAtom = (DirectionalAtom *)atoms[i];
87    
88     // get and convert the torque to body frame
89    
90     Tb[0] = dAtom->getTx();
91     Tb[1] = dAtom->getTy();
92     Tb[2] = dAtom->getTz();
93    
94     dAtom->lab2Body( Tb );
95    
96     // get the angular momentum, and propagate a half step
97    
98     ji[0] = dAtom->getJx();
99     ji[1] = dAtom->getJy();
100     ji[2] = dAtom->getJz();
101    
102     ji[0] += dt2 * (Tb[0] * eConvert - ji[0]*chi);
103     ji[1] += dt2 * (Tb[1] * eConvert - ji[1]*chi);
104     ji[2] += dt2 * (Tb[2] * eConvert - ji[2]*chi);
105    
106     // use the angular velocities to propagate the rotation matrix a
107     // full time step
108    
109     // rotate about the x-axis
110     angle = dt2 * ji[0] / dAtom->getIxx();
111     this->rotate( 1, 2, angle, ji, &Amat[aMatIndex] );
112    
113     // rotate about the y-axis
114     angle = dt2 * ji[1] / dAtom->getIyy();
115     this->rotate( 2, 0, angle, ji, &Amat[aMatIndex] );
116    
117     // rotate about the z-axis
118     angle = dt * ji[2] / dAtom->getIzz();
119     this->rotate( 0, 1, angle, ji, &Amat[aMatIndex] );
120    
121     // rotate about the y-axis
122     angle = dt2 * ji[1] / dAtom->getIyy();
123     this->rotate( 2, 0, angle, ji, &Amat[aMatIndex] );
124    
125     // rotate about the x-axis
126     angle = dt2 * ji[0] / dAtom->getIxx();
127     this->rotate( 1, 2, angle, ji, &Amat[aMatIndex] );
128    
129     dAtom->setJx( ji[0] );
130     dAtom->setJy( ji[1] );
131     dAtom->setJz( ji[2] );
132     }
133    
134     }
135     }
136    
137     void NPTi::moveB( void ){
138     int i,j,k;
139     int atomIndex;
140     DirectionalAtom* dAtom;
141     double Tb[3];
142     double ji[3];
143     double instaTemp, instaPress, instaVol;
144     double tt2, tb2;
145    
146     tt2 = tauThermostat * tauThermostat;
147     tb2 = tauBarostat * tauBarostat;
148    
149     instaTemp = tStats->getTemperature();
150     instaPress = tStats->getPressure();
151     instaVol = tStats->getVolume();
152    
153     chi += dt2 * ( instaTemp / targetTemp - 1.0) / tt2;
154     eta += dt2 * ( instaVol * (instaPress - targetPressure) / (NkBT*tb2));
155    
156     for( i=0; i<nAtoms; i++ ){
157     atomIndex = i * 3;
158    
159     // velocity half step
160     for( j=atomIndex; j<(atomIndex+3); j++ )
161     for( j=atomIndex; j<(atomIndex+3); j++ )
162     vel[j] += dt2 * ((frc[j]/atoms[i]->getMass())*eConvert
163     - vel[j]*(chi+eta));
164    
165     if( atoms[i]->isDirectional() ){
166    
167     dAtom = (DirectionalAtom *)atoms[i];
168    
169     // get and convert the torque to body frame
170    
171     Tb[0] = dAtom->getTx();
172     Tb[1] = dAtom->getTy();
173     Tb[2] = dAtom->getTz();
174    
175     dAtom->lab2Body( Tb );
176    
177     // get the angular momentum, and complete the angular momentum
178     // half step
179    
180     ji[0] = dAtom->getJx();
181     ji[1] = dAtom->getJy();
182     ji[2] = dAtom->getJz();
183    
184     ji[0] += dt2 * (Tb[0] * eConvert - ji[0]*chi);
185     ji[1] += dt2 * (Tb[1] * eConvert - ji[1]*chi);
186     ji[2] += dt2 * (Tb[2] * eConvert - ji[2]*chi);
187    
188     dAtom->setJx( ji[0] );
189     dAtom->setJy( ji[1] );
190     dAtom->setJz( ji[2] );
191     }
192     }
193     }
194    
195     int NPTi::readyCheck() {
196    
197     // First check to see if we have a target temperature.
198     // Not having one is fatal.
199    
200     if (!have_target_temp) {
201     sprintf( painCave.errMsg,
202     "NPTi error: You can't use the NPTi integrator\n"
203     " without a targetTemp!\n"
204     );
205     painCave.isFatal = 1;
206     simError();
207     return -1;
208     }
209    
210     if (!have_target_pressure) {
211     sprintf( painCave.errMsg,
212     "NPTi error: You can't use the NPTi integrator\n"
213     " without a targetPressure!\n"
214     );
215     painCave.isFatal = 1;
216     simError();
217     return -1;
218     }
219    
220     // We must set tauThermostat.
221    
222     if (!have_tau_thermostat) {
223     sprintf( painCave.errMsg,
224     "NPTi error: If you use the NPTi\n"
225     " integrator, you must set tauThermostat.\n");
226     painCave.isFatal = 1;
227     simError();
228     return -1;
229     }
230    
231     // We must set tauBarostat.
232    
233     if (!have_tau_barostat) {
234     sprintf( painCave.errMsg,
235     "NPTi error: If you use the NPTi\n"
236     " integrator, you must set tauBarostat.\n");
237     painCave.isFatal = 1;
238     simError();
239     return -1;
240     }
241    
242     // We need NkBT a lot, so just set it here:
243    
244     NkBT = (double)info->ndf * kB * targetTemp;
245    
246     return 1;
247     }