diff --git a/src/MBPT/regularized_self_energy_correlation_diag.f90 b/src/MBPT/regularized_self_energy_correlation_diag.f90
new file mode 100644
index 0000000..d0dba7d
--- /dev/null
+++ b/src/MBPT/regularized_self_energy_correlation_diag.f90
@@ -0,0 +1,124 @@
+subroutine regularized_self_energy_correlation_diag(COHSEX,eta,nBas,nC,nO,nV,nR,nS,e,Omega,rho,EcGM,SigC)
+
+! Compute diagonal of the correlation part of the regularized self-energy
+
+  implicit none
+  include 'parameters.h'
+
+! Input variables
+
+  logical,intent(in)            :: COHSEX
+  double precision,intent(in)   :: eta
+  integer,intent(in)            :: nBas
+  integer,intent(in)            :: nC
+  integer,intent(in)            :: nO
+  integer,intent(in)            :: nV
+  integer,intent(in)            :: nR
+  integer,intent(in)            :: nS
+  double precision,intent(in)   :: e(nBas)
+  double precision,intent(in)   :: Omega(nS)
+  double precision,intent(in)   :: rho(nBas,nBas,nS)
+
+! Local variables
+
+  integer                       :: i,a,p,q,jb
+  double precision              :: eps
+  double precision,external     :: SigC_dcgw
+
+  double precision              :: kappa
+  double precision              :: fk
+
+! Output variables
+
+  double precision,intent(out)  :: SigC(nBas)
+  double precision,intent(out)  :: EcGM
+
+! Initialize 
+
+  SigC(:) = 0d0
+
+!---------------------------------------------!
+! Parameters for regularized MP2 calculations !
+!---------------------------------------------!
+
+  kappa = 1.1d0
+
+!-----------------------------
+! COHSEX static self-energy
+!-----------------------------
+
+  if(COHSEX) then
+
+    ! COHSEX: SEX part of the COHSEX correlation self-energy
+
+    do p=nC+1,nBas-nR
+      do i=nC+1,nO
+        do jb=1,nS
+          SigC(p) = SigC(p) + 4d0*rho(p,i,jb)**2/Omega(jb)
+        end do
+      end do
+    end do
+ 
+    ! COHSEX: COH part of the COHSEX correlation self-energy
+ 
+    do p=nC+1,nBas-nR
+      do q=nC+1,nBas-nR
+        do jb=1,nS
+          SigC(p) = SigC(p) - 2d0*rho(p,q,jb)**2/Omega(jb)
+        end do
+      end do
+    end do
+
+    ! GM correlation energy
+
+    EcGM = 0d0
+    do i=nC+1,nO
+      EcGM = EcGM - SigC(i)
+    end do
+
+!-----------------------------
+! GW self-energy
+!-----------------------------
+
+  else
+ 
+    ! Occupied part of the correlation self-energy
+ 
+    do p=nC+1,nBas-nR
+      do i=nC+1,nO
+        do jb=1,nS
+          eps = e(p) - e(i) + Omega(jb)
+          fk  = (1d0 - exp(-kappa*eps))**2/eps
+          SigC(p) = SigC(p) + 2d0*rho(p,i,jb)**2*fk
+        end do
+      end do
+    end do
+ 
+    ! Virtual part of the correlation self-energy
+ 
+    do p=nC+1,nBas-nR
+      do a=nO+1,nBas-nR
+        do jb=1,nS
+          eps = e(p) - e(a) - Omega(jb)
+          fk  = (1d0 - exp(-kappa*eps))**2/eps
+          SigC(p) = SigC(p) + 2d0*rho(p,a,jb)**2*fk
+        end do
+      end do
+    end do
+
+    ! GM correlation energy
+
+    EcGM = 0d0
+    do i=nC+1,nO
+      do a=nO+1,nBas-nR
+        do jb=1,nS
+          eps = e(a) - e(i) + Omega(jb)
+          fk  = (1d0 - exp(-kappa*eps))**2/eps
+          EcGM = EcGM - 4d0*rho(a,i,jb)**2*fk
+        end do
+      end do
+    end do
+
+  end if
+
+end subroutine regularized_self_energy_correlation_diag
diff --git a/src/MP/MP2.f90 b/src/MP/MP2.f90
index cfca705..30e857e 100644
--- a/src/MP/MP2.f90
+++ b/src/MP/MP2.f90
@@ -72,9 +72,9 @@ subroutine MP2(nBas,nC,nO,nV,nR,ERI,ENuc,EHF,e,EcMP2)
 
           ! Second-order ring diagram
 
-          fs  = (1d0 - exp(-kappa*Dijab))/Dijab
-          fs2 = (1d0 - exp(-sigm1*Dijab*Dijab))/Dijab
-          fk  = (1d0 - exp(-sigm2*Dijab))**2/Dijab
+          fs  = (1d0 - exp(-sigm1*Dijab))/Dijab
+          fs2 = (1d0 - exp(-sigm2*Dijab*Dijab))/Dijab
+          fk  = (1d0 - exp(-kappa*Dijab))**2/Dijab
 
           E2d   = E2d   - ERI(i,j,a,b)*ERI(i,j,a,b)/Dijab
           E2ds  = E2ds  - ERI(i,j,a,b)*ERI(i,j,a,b)*fs