--- trunk/OOPSE/libmdtools/Thermo.cpp	2003/07/09 15:33:46	582
+++ trunk/OOPSE/libmdtools/Thermo.cpp	2003/07/10 17:10:56	588
@@ -138,12 +138,12 @@ double Thermo::getEnthalpy() {
 
   const double e_convert = 4.184E-4; // convert kcal/mol -> (amu A^2)/fs^2
   double u, p, v;
-  double press[9];
+  double press[3][3];
 
   u = this->getTotalE();
 
   this->getPressureTensor(press);
-  p = (press[0] + press[4] + press[8]) / 3.0;
+  p = (press[0][0] + press[1][1] + press[2][2]) / 3.0;
 
   v = this->getVolume();
 
@@ -160,18 +160,18 @@ double Thermo::getPressure() {
   // Relies on the calculation of the full molecular pressure tensor
   
   const double p_convert = 1.63882576e8;
-  double press[9];
+  double press[3][3];
   double pressure;
 
   this->getPressureTensor(press);
 
-  pressure = p_convert * (press[0] + press[4] + press[8]) / 3.0;
+  pressure = p_convert * (press[0][0] + press[1][1] + press[2][2]) / 3.0;
 
   return pressure;
 }
 
 
-void Thermo::getPressureTensor(double press[9]){
+void Thermo::getPressureTensor(double press[3][3]){
   // returns pressure tensor in units amu*fs^-2*Ang^-1
   // routine derived via viral theorem description in:
   // Paci, E. and Marchi, M. J.Phys.Chem. 1996, 100, 4314-4322
@@ -181,9 +181,7 @@ void Thermo::getPressureTensor(double press[9]){
   double molmass, volume;
   double vcom[3];
   double p_local[9], p_global[9];
-  double theBox[3];
-  //double* tau;
-  int i, nMols;
+  int i, j, k, nMols;
   Molecule* molecules;
 
   nMols = entry_plug->n_mol;
@@ -222,8 +220,11 @@ void Thermo::getPressureTensor(double press[9]){
 
   volume = entry_plug->boxVol;
 
-  for(i=0; i<9; i++) {
-    press[i] = (p_global[i] - entry_plug->tau[i]*e_convert) / volume;
+  for(i = 0; i < 3; i++) {
+    for (j = 0; j < 3; j++) {
+      k = 3*i + j;
+      press[i][j] = (p_global[k] - entry_plug->tau[k]*e_convert) / volume;
+    }
   }
 }