Fixed x_coeff in RSHFunctional.C Cleanup & comment

src/ExchangeOperator.C

@@ -15,6 +15,18 @@
 // ExchangeOperator.C
 //
 ////////////////////////////////////////////////////////////////////////////////
+//
+// Screened exchange operator
+// Diagonal screening is used with interaction potential
+// vint(r) = alpha_sx  * erf(mu_sx*r)/r + beta_sx * erfc(mu_sx*r)/r
+// The parameters alpha_sx, beta_sx and mu_sx are provided to the constructor
+//
+// Special cases:
+// alpha_sx = beta_sx = 0: no interaction
+// alpha_sx = beta_sx: Coulomb potential with prefactor alpha_sx (= beta_sx)
+// alpha_sx = 0, beta_sx = 0.25, mu = 0.11: HSE
+//
+////////////////////////////////////////////////////////////////////////////////
 
 #include <iostream>
 #include <fstream>
@@ -39,7 +51,6 @@ ExchangeOperator::ExchangeOperator( Sample& s, double alpha_sx,
   double beta_sx, double mu_sx ) :
   s_(s), wf0_(s.wf), dwf0_(s.wf), wfc_(s.wf),
   alpha_sx_(alpha_sx), beta_sx_(beta_sx), mu_sx_(mu_sx),
-  coulomb_(alpha_sx==beta_sx),
   gcontext_(s.wf.sd(0,0)->context())
 {
   // check validity of the values of alpha_sx, beta_sx, mu_sx

src/ExchangeOperator.h

@@ -177,9 +177,6 @@ class ExchangeOperator
   double dvint(double g2);
   double vint_div_scal(double rc);
 
-  // coulomb potential flag (true if alpha_sx==beta_sx)
-  bool coulomb_;
-
   public:
 
   // constructor

src/RSHFunctional.C

@@ -50,9 +50,8 @@ const double A = 1.0161144, B = -0.37170836, C = -0.077215461, D = 0.57786348,
 // constructor
 RSHFunctional::RSHFunctional(const vector<vector<double> > &rhoe,
   double alpha_RSH, double beta_RSH, double mu_RSH):
-//!! todo: remove x_coeff and c_coeff initialization in next line
-  x_coeff_(0.75), c_coeff_(1.0), alpha_RSH_(alpha_RSH), beta_RSH_(beta_RSH),
-  mu_RSH_(mu_RSH), omega(mu_RSH)
+  alpha_RSH_(alpha_RSH), beta_RSH_(beta_RSH), mu_RSH_(mu_RSH), omega(mu_RSH),
+  x_coeff_(1.0-beta_RSH), c_coeff_(1.0)
 {
   // nonmagnetic or magnetic
   _nspin = rhoe.size();