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root/group/trunk/OOPSE/libmdtools/NVT.cpp
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Comparing trunk/OOPSE/libmdtools/NVT.cpp (file contents):
Revision 561 by mmeineke, Fri Jun 20 20:29:36 2003 UTC vs.
Revision 565 by gezelter, Tue Jun 24 22:51:57 2003 UTC

# Line 14 | Line 14 | NVT::NVT ( SimInfo *theInfo, ForceFields* the_ff):
14   NVT::NVT ( SimInfo *theInfo, ForceFields* the_ff):
15    Integrator( theInfo, the_ff )
16   {
17 <  zeta = 0.0;
17 >  chi = 0.0;
18    have_tau_thermostat = 0;
19    have_target_temp = 0;
20 –  have_qmass = 0;
20   }
21  
22   void NVT::moveA() {
# Line 27 | Line 26 | void NVT::moveA() {
26    DirectionalAtom* dAtom;
27    double Tb[3];
28    double ji[3];
29 <  double ke;
29 >  double instTemp;
30    double angle;
31  
32 +  instTemp = tStats->getTemperature();
33  
34 <  ke = tStats->getKinetic() * eConvert;
35 <  zeta += dt2 * ( (2.0 * ke  -  NkBT) / qmass );
34 >  // first evolve chi a half step
35 >  
36 >  chi += dt2 * ( instTemp / targetTemp - 1.0) / (tauThermostat*tauThermostat);
37  
38    for( i=0; i<nAtoms; i++ ){
39      atomIndex = i * 3;
# Line 40 | Line 41 | void NVT::moveA() {
41      
42      // velocity half step
43      for( j=atomIndex; j<(atomIndex+3); j++ )
44 <      vel[j] += dt2 * ((frc[j]/atoms[i]->getMass())*eConvert - vel[j]*zeta);
44 >      vel[j] += dt2 * ((frc[j]/atoms[i]->getMass())*eConvert - vel[j]*chi);
45  
46      // position whole step    
47      for( j=atomIndex; j<(atomIndex+3); j++ )
# Line 65 | Line 66 | void NVT::moveA() {
66        ji[1] = dAtom->getJy();
67        ji[2] = dAtom->getJz();
68        
69 <      ji[0] += dt2 * (Tb[0] * eConvert - ji[0]*zeta);
70 <      ji[1] += dt2 * (Tb[1] * eConvert - ji[1]*zeta);
71 <      ji[2] += dt2 * (Tb[2] * eConvert - ji[2]*zeta);
69 >      ji[0] += dt2 * (Tb[0] * eConvert - ji[0]*chi);
70 >      ji[1] += dt2 * (Tb[1] * eConvert - ji[1]*chi);
71 >      ji[2] += dt2 * (Tb[2] * eConvert - ji[2]*chi);
72        
73        // use the angular velocities to propagate the rotation matrix a
74        // full time step
# Line 106 | Line 107 | void NVT::moveB( void ){
107    DirectionalAtom* dAtom;
108    double Tb[3];
109    double ji[3];
110 <  double ke;
110 >  double instTemp;
111    
112 <
113 <  ke = tStats->getKinetic() * eConvert;
113 <  zeta += dt2 * ( (2.0 * ke  -  NkBT) / qmass );
112 >  instTemp = tStats->getTemperature();
113 >  chi += dt2 * ( instTemp / targetTemp - 1.0) / (tauThermostat*tauThermostat);
114    
115    for( i=0; i<nAtoms; i++ ){
116      atomIndex = i * 3;
117      
118      // velocity half step
119      for( j=atomIndex; j<(atomIndex+3); j++ )
120 <      vel[j] += dt2 * ((frc[j]/atoms[i]->getMass())*eConvert - vel[j]*zeta);
120 >      vel[j] += dt2 * ((frc[j]/atoms[i]->getMass())*eConvert - vel[j]*chi);
121      
122      if( atoms[i]->isDirectional() ){
123        
# Line 138 | Line 138 | void NVT::moveB( void ){
138        ji[1] = dAtom->getJy();
139        ji[2] = dAtom->getJz();
140        
141 <      ji[0] += dt2 * (Tb[0] * eConvert - ji[0]*zeta);
142 <      ji[1] += dt2 * (Tb[1] * eConvert - ji[1]*zeta);
143 <      ji[2] += dt2 * (Tb[2] * eConvert - ji[2]*zeta);
141 >      ji[0] += dt2 * (Tb[0] * eConvert - ji[0]*chi);
142 >      ji[1] += dt2 * (Tb[1] * eConvert - ji[1]*chi);
143 >      ji[2] += dt2 * (Tb[2] * eConvert - ji[2]*chi);
144        
145        dAtom->setJx( ji[0] );
146        dAtom->setJy( ji[1] );
# Line 162 | Line 162 | int NVT::readyCheck() {
162      simError();
163      return -1;
164    }
165 <    
166 <  // Next check to see that we have a reasonable number of degrees of freedom
167 <  // and then set NkBT if we do have it.   Unreasonable numbers of DOFs
168 <  // are also fatal.
169 <
170 <  if (info->ndf > 0) {
171 <    NkBT = (double)info->ndf * kB * targetTemp;
172 <  } else {
165 >  
166 >  // We must set tauThermostat.
167 >  
168 >  if (!have_tau_thermostat) {
169      sprintf( painCave.errMsg,
170 <             "NVT error: We got a silly number of degrees of freedom!\n"
171 <             );
170 >             "NVT error: If you use the constant temperature\n"
171 >             "   integrator, you must set tauThermostat.\n");
172      painCave.isFatal = 1;
173      simError();
174      return -1;
175 <  }
180 <    
181 <  // We have our choice on setting qmass or tauThermostat.  One of them
182 <  // must be set.
183 <
184 <  if (!have_qmass) {
185 <    if (have_tau_thermostat) {
186 <      sprintf( painCave.errMsg,
187 <               "NVT info: Setting qMass = %lf\n", tauThermostat * NkBT);
188 <      this->setQmass(tauThermostat * NkBT);      
189 <      painCave.isFatal = 0;
190 <      simError();
191 <    } else {
192 <      sprintf( painCave.errMsg,
193 <               "NVT error: If you use the constant temperature\n"
194 <               "   integrator, you must set either tauThermostat or qMass.\n");
195 <      painCave.isFatal = 1;
196 <      simError();
197 <      return -1;
198 <    }
199 <  }
200 <  
175 >  }    
176    return 1;
177   }
178  

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