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root/group/trunk/OOPSE/libmdtools/Thermo.cpp
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Comparing trunk/OOPSE/libmdtools/Thermo.cpp (file contents):
Revision 479 by chuckv, Tue Apr 8 15:20:44 2003 UTC vs.
Revision 572 by mmeineke, Wed Jul 2 21:26:55 2003 UTC

# Line 134 | Line 134 | double Thermo::getPressure(){
134    return temperature;
135   }
136  
137 < double Thermo::getPressure(){
138 <  // returns pressure in units amu*fs^-2*Ang^-1
137 > double Thermo::getEnthalpy() {
138 >
139 >  const double e_convert = 4.184E-4; // convert kcal/mol -> (amu A^2)/fs^2
140 >  double u, p, v;
141 >  double press[9];
142 >
143 >  u = this->getTotalE();
144 >
145 >  this->getPressureTensor(press);
146 >  p = (press[0] + press[4] + press[8]) / 3.0;
147 >
148 >  v = this->getVolume();
149 >
150 >  return (u + (p*v)/e_convert);
151 > }
152 >
153 > double Thermo::getVolume() {
154 >  return entry_plug->boxVol;
155 > }
156 >
157 > double Thermo::getPressure() {
158 >  // returns the pressure in units of atm
159 >  // Relies on the calculation of the full molecular pressure tensor
160 >  
161 >  const double p_convert = 1.63882576e8;
162 >  double press[9];
163 >  double pressure;
164 >
165 >  this->getPressureTensor(press);
166 >
167 >  pressure = p_convert * (press[0] + press[4] + press[8]) / 3.0;
168 >
169 >  return pressure;
170 > }
171 >
172 >
173 > void Thermo::getPressureTensor(double press[9]){
174 >  // returns pressure tensor in units amu*fs^-2*Ang^-1
175    // routine derived via viral theorem description in:
176    // Paci, E. and Marchi, M. J.Phys.Chem. 1996, 100, 4314-4322
177  
178    const double e_convert = 4.184e-4;
179 <  const double p_convert = 1.63882576e8;
180 <  double molmass;
181 <  double vcom[3];
182 <  double p_local, p_sum, p_mol, virial;
179 >
180 >  double molmass, volume;
181 >  double vcom[3];
182 >  double p_local[9], p_global[9];
183    double theBox[3];
184 <  double* tau;
184 >  //double* tau;
185    int i, nMols;
186    Molecule* molecules;
187  
188    nMols = entry_plug->n_mol;
189    molecules = entry_plug->molecules;
190 <  tau = entry_plug->tau;
190 >  //tau = entry_plug->tau;
191  
192    // use velocities of molecular centers of mass and molecular masses:
193 <  p_local = 0.0;
193 >  for (i=0; i < 9; i++) {    
194 >    p_local[i] = 0.0;
195 >    p_global[i] = 0.0;
196 >  }
197  
198    for (i=0; i < nMols; i++) {
199      molmass = molecules[i].getCOMvel(vcom);
200 <    p_local += (vcom[0]*vcom[0] + vcom[1]*vcom[1] + vcom[2]*vcom[2]) * molmass;
200 >
201 >    p_local[0] += molmass * (vcom[0] * vcom[0]);
202 >    p_local[1] += molmass * (vcom[0] * vcom[1]);
203 >    p_local[2] += molmass * (vcom[0] * vcom[2]);
204 >    p_local[3] += molmass * (vcom[1] * vcom[0]);
205 >    p_local[4] += molmass * (vcom[1] * vcom[1]);
206 >    p_local[5] += molmass * (vcom[1] * vcom[2]);
207 >    p_local[6] += molmass * (vcom[2] * vcom[0]);
208 >    p_local[7] += molmass * (vcom[2] * vcom[1]);
209 >    p_local[8] += molmass * (vcom[2] * vcom[2]);
210    }
211  
212    // Get total for entire system from MPI.
213  
214   #ifdef IS_MPI
215 <  MPI_Allreduce(&p_local,&p_sum,1,MPI_DOUBLE, MPI_SUM, MPI_COMM_WORLD);
215 >  MPI_Allreduce(p_local,p_global,9,MPI_DOUBLE, MPI_SUM, MPI_COMM_WORLD);
216   #else
217 <  p_sum = p_local;
217 >  for (i=0; i<9; i++) {
218 >    p_global[i] = p_local[i];
219 >  }
220   #endif // is_mpi
221  
222 <  virial = tau[0] + tau[4] + tau[8];
173 <  entry_plug->getBox(theBox);
222 >  volume = entry_plug->boxVol;
223  
224 <  p_mol = p_convert * (p_sum - virial*e_convert) /
225 <    (3.0 * theBox[0] * theBox[1]* theBox[2]);
226 <
178 <  return p_mol;
224 >  for(i=0; i<9; i++) {
225 >    press[i] = (p_global[i] - entry_plug->tau[i]*e_convert) / volume;
226 >  }
227   }
228  
229   void Thermo::velocitize() {

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