From c0da0893700b3747dbfb34b824162800a4613d07 Mon Sep 17 00:00:00 2001
From: pfloos <pierrefrancois.loos@gmail.com>
Date: Mon, 24 Jul 2023 21:45:51 +0200
Subject: [PATCH] ppBSE dynamic kernel B and D

---
 src/GW/GW_ppBSE_dynamic_kernel_B.f90 | 131 +++++++++++++++++++++++++++
 1 file changed, 131 insertions(+)
 create mode 100644 src/GW/GW_ppBSE_dynamic_kernel_B.f90

diff --git a/src/GW/GW_ppBSE_dynamic_kernel_B.f90 b/src/GW/GW_ppBSE_dynamic_kernel_B.f90
new file mode 100644
index 0000000..424ded1
--- /dev/null
+++ b/src/GW/GW_ppBSE_dynamic_kernel_B.f90
@@ -0,0 +1,131 @@
+subroutine GW_ppBSE_dynamic_kernel_B(ispin,eta,nBas,nC,nO,nV,nR,nS,nOO,nVV,lambda,eGW,Om,rho,OmBSE,KB_dyn)
+
+! Compute the dynamic part of the Bethe-Salpeter equation matrices
+
+  implicit none
+  include 'parameters.h'
+
+! Input variables
+
+  integer,intent(in)            :: ispin
+  integer,intent(in)            :: nBas
+  integer,intent(in)            :: nC
+  integer,intent(in)            :: nO
+  integer,intent(in)            :: nV
+  integer,intent(in)            :: nR
+  integer,intent(in)            :: nS
+  integer,intent(in)            :: nOO
+  integer,intent(in)            :: nVV
+  double precision,intent(in)   :: eta
+  double precision,intent(in)   :: lambda
+  double precision,intent(in)   :: eGW(nBas)
+  double precision,intent(in)   :: Om(nS)
+  double precision,intent(in)   :: rho(nBas,nBas,nS)
+  double precision,intent(in)   :: OmBSE
+  
+! Local variables
+
+  double precision              :: dem,num
+  integer                       :: m
+  integer                       :: a,b,i,j
+  integer                       :: ab,ij
+
+! Output variables
+
+  double precision,intent(out)  :: KB_dyn(nVV,nOO)
+
+! Initialization
+
+  KB_dyn(:,:) = 0d0
+
+! Build dynamic A matrix
+
+  if(ispin == 1) then
+
+    ab = 0
+    do a=nO+1,nBas-nR
+      do b=a,nBas-nR
+        ab = ab + 1
+ 
+        ij = 0
+        do i=nC+1,nO
+          do j=i,nO     
+            ij = ij + 1
+  
+            do m=1,nS
+
+              dem = eGW(j) - Om(m) - eGW(b)
+              num = rho(a,i,m)*rho(b,j,m)
+
+              KB_dyn(ab,ij) = KB_dyn(ab,ij) + num*dem/(dem**2 + eta**2)
+
+              dem = eGW(j) - Om(m) - eGW(a)
+              num = rho(b,i,m)*rho(a,j,m)
+
+              KB_dyn(ab,ij) = KB_dyn(ab,ij) - num*dem/(dem**2 + eta**2)
+
+              dem = eGW(i) - Om(m) - eGW(a)
+              num = rho(a,i,m)*rho(b,j,m)
+
+              KB_dyn(ab,ij) = KB_dyn(ab,ij) + num*dem/(dem**2 + eta**2)
+
+              dem = eGW(i) - Om(m) - eGW(b)
+              num = rho(b,i,m)*rho(a,j,m)
+
+              KB_dyn(ab,ij) = KB_dyn(ab,ij) - num*dem/(dem**2 + eta**2)
+
+            end do
+
+          end do
+        end do
+
+      end do
+    end do
+
+  end if
+
+ if(ispin == 2) then
+
+    ab = 0
+    do a=nO+1,nBas-nR
+      do b=a+1,nBas-nR
+        ab = ab + 1
+ 
+        ij = 0
+        do i=nC+1,nO
+          do j=i+1,nO     
+            ij = ij + 1
+  
+            do m=1,nS
+
+              dem = eGW(j) - Om(m) - eGW(b)
+              num = rho(a,i,m)*rho(b,j,m)
+
+              KB_dyn(ab,ij) = KB_dyn(ab,ij) + num*dem/(dem**2 + eta**2)
+
+              dem = eGW(j) - Om(m) - eGW(a)
+              num = rho(b,i,m)*rho(a,j,m)
+
+              KB_dyn(ab,ij) = KB_dyn(ab,ij) - num*dem/(dem**2 + eta**2)
+
+              dem = eGW(i) - Om(m) - eGW(a)
+              num = rho(a,i,m)*rho(b,j,m)
+
+              KB_dyn(ab,ij) = KB_dyn(ab,ij) + num*dem/(dem**2 + eta**2)
+
+              dem = eGW(i) - Om(m) - eGW(b)
+              num = rho(b,i,m)*rho(a,j,m)
+
+              KB_dyn(ab,ij) = KB_dyn(ab,ij) - num*dem/(dem**2 + eta**2)
+
+            end do
+
+          end do
+        end do
+
+      end do
+    end do
+
+  end if
+
+end subroutine