diff --git a/resultsFile/Modules/gamessFile.py b/resultsFile/Modules/gamessFile.py
index f7ce2d0..4b4376f 100755
--- a/resultsFile/Modules/gamessFile.py
+++ b/resultsFile/Modules/gamessFile.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
-#   resultsFile is a library which allows to read output files of quantum 
+#   resultsFile is a library which allows to read output files of quantum
 #   chemistry codes and write input files.
-#   Copyright (C) 2007 Anthony SCEMAMA 
+#   Copyright (C) 2007 Anthony SCEMAMA
 #
 #   This program is free software; you can redistribute it and/or modify
 #   it under the terms of the GNU General Public License as published by
@@ -18,11 +18,11 @@
 #   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 #
 #   Anthony Scemama
-#   LCPQ - IRSAMC        
+#   LCPQ - IRSAMC
 #   Universite Paul Sabatier
-#   118, route de Narbonne      
-#   31062 Toulouse Cedex 4      
-#   scemama@irsamc.ups-tlse.fr 
+#   118, route de Narbonne
+#   31062 Toulouse Cedex 4
+#   scemama@irsamc.ups-tlse.fr
 
 
 
@@ -297,7 +297,7 @@ class gamessFile(resultsFile.resultsFileX):
                   occ[motype][i] = mo.eigenvalue
         if occ != {}:
           self._occ_num = occ
-     return self._occ_num 
+     return self._occ_num
 
    def get_options(self):
      if self._options is None:
@@ -457,7 +457,7 @@ class gamessFile(resultsFile.resultsFileX):
            assert label == i.name
            f = list(map(float,buffer[2:]))
            self._gradient_energy.append(f)
-           pos +=1 
+           pos +=1
        except IndexError:
          self._gradient_energy = []
      return self._gradient_energy
@@ -590,7 +590,7 @@ class gamessFile(resultsFile.resultsFileX):
            self._point_group = group.replace('N',line[6])
         except IndexError:
            pass
-     return self._point_group 
+     return self._point_group
 
    def get_geometry(self):
      if self._geometry is None:
@@ -634,7 +634,7 @@ class gamessFile(resultsFile.resultsFileX):
         except IndexError:
            pass
      return self._dipole
-   
+
    def get_basis(self):
      if self._basis is None:
         try:
@@ -691,7 +691,7 @@ class gamessFile(resultsFile.resultsFileX):
 #                for (i, s, b) in atom:
 #                    new_basis_read += [ [ib, s, b] ]
 #                    ib += 1
-#          
+#
 #        basis_read = new_basis_read
 
         new_basis_read = []
@@ -784,7 +784,7 @@ class gamessFile(resultsFile.resultsFileX):
    def get_mo_types(self):
       if self._mo_types is None:
         self.get_mo_sets()
-      return self._mo_types 
+      return self._mo_types
 
    def get_atom_to_ao_range(self):
       try:
@@ -1219,12 +1219,12 @@ class gamessFile(resultsFile.resultsFileX):
    def get_num_alpha(self):
       if self._num_alpha is None:
          self._num_alpha = (self.num_elec + self.multiplicity-1)//2
-      return self._num_alpha 
+      return self._num_alpha
 
    def get_num_beta(self):
       if self._num_beta is None:
          self._num_beta = (self.num_elec - self.multiplicity+1)//2
-      return self._num_beta 
+      return self._num_beta
 
    def get_determinants_mo_type(self):
       if self._determinants_mo_type is None:
@@ -1301,12 +1301,25 @@ class gamessFile(resultsFile.resultsFileX):
                    mo = []
                    for i in mostr:
                      mo.append (int(i))
-                   p_count=0
-                   for j in range ( len(mo) ):
-                     if mo[j] < 0:
-                       for l in range ( j+1, len(mo) ):
-                         if mo[l] > 0:
-                           p_count+=1
+                   # Calculate the phase based on the the number of swaps in the determinant
+                   p_count=0; done = False
+                   while (not done):
+                     swaps = 0
+                     for j in range ( len(mo) -1 ):
+                       if (abs(mo[j]) > abs(mo[j+1])):
+                         tmp = mo[j]
+                         mo[j] = mo[j+1]
+                         mo[j+1] = tmp
+                         swaps += 1
+                       elif (abs(mo[j]) == abs(mo[j+1])):
+                         if (mo[j] < 0):
+                           mo[j] = -mo[j]
+                           mo[j+1] = -mo[j+1]
+                           swaps += 1
+                     if (swaps == 0):
+                       done = True
+                     else:
+                       p_count += swaps
                    coef = float (buffer[0])*(-1.0)**p_count
                    tempcsf_a = []
                    tempcsf_b = []
@@ -1396,7 +1409,7 @@ class gamessFile(resultsFile.resultsFileX):
            self.options['SCFTYP'] == 'UHF' or\
            self.options['SCFTYP'] == 'ROHF':
            self._csf_coefficients = [ [1.] ]
-        # Multi-determinant case 
+        # Multi-determinant case
         elif self.options['CITYP'] == 'GUGA' or self.options['SCFTYP'] == 'MCSCF':
            self._csf_coefficients = [ [] for i in range(self.num_states) ]
            self._pos = 0
@@ -1518,7 +1531,7 @@ def set_%(i)s(self,value): self._%(i)s = value
            self._file = fortranBinary(filename,"rb")
 
         def get_form(self):
-           return self._file.form 
+           return self._file.form
 
         def set_form(self,form):
            self._file.form = form
@@ -1619,7 +1632,7 @@ def gamess_write_vec(res, file):
          monum = monum[-2:]
          fields.append ( monum )
          linum = "%4d"%(line)
-         linum = linum[-3:] 
+         linum = linum[-3:]
          fields.append ( linum )
          for n in range(5):
            try:
@@ -1690,7 +1703,7 @@ def gamess_write_data(res, file):
 
 def gamess_write_integrals(res,file):
   filename = file.name.replace('.inp','.moints')
-      
+
 def write_gamess(file,stdout):
   gamess_write_contrl(file,stdout)
   x = file.basis
@@ -1698,7 +1711,7 @@ def write_gamess(file,stdout):
   gamess_write_data(file,stdout)
   gamess_write_vec(file,stdout)
 
-  
+
 resultsFile.fileTypes.append(gamessFile)
 
 if __name__ == '__main__':