>50% acceleration of int.f90

src/Pseudo_integrals/int.f90

@@ -1898,11 +1898,17 @@ end
 !!
 !!    M_n(x) modified spherical bessel function 
 !!
+
 double precision function int_prod_bessel(l,gam,n,m,a,b,arg)
+
   implicit none
   integer n,k,m,q,l,kcp
   double precision gam,dblefact,fact,pi,a,b
   double precision int,intold,sum,coef_nk,crochet,u,int_prod_bessel_large,freal,arg
+  double precision dump
+
+  double precision, allocatable :: temp_array(:)
+
   logical done
 
   u=(a+b)/(2.d0*dsqrt(gam))
@@ -1913,6 +1919,7 @@ end
       int_prod_bessel=0.d0
       return
     endif
+    
     int_prod_bessel=crochet(l,gam)*freal
     return
   endif
@@ -1929,30 +1936,48 @@ end
     int=0.d0
     done=.false.
     kcp=0
+
+    allocate( temp_array(0:101))
+
     do while (.not.done)  
+
       kcp=kcp+1
       sum=0.d0
-        do k=0,q
+
-         sum=sum+coef_nk(n,k)*coef_nk(m,q-k)*a**(n+2*k)*b**(m-2*k+2*q)
+      dump = a**n
+      do k=q,q+1
+         temp_array(k) = coef_nk(n,k)*dump*(a**(2*k))
       enddo
+
+      do k=0,q
+        sum=sum+temp_array(k)*coef_nk(m,q-k)*b**(m-2*k+2*q)
+      enddo
+     
      int=int+sum*crochet(2*q+n+m+l,gam)
+     
      if(dabs(int-intold).lt.1d-15)then
        done=.true.
       else
+        
         q=q+1
         intold=int
       endif
+
     enddo
+    
+    deallocate(temp_array)
+
     int_prod_bessel=int*freal
+    
     if(kcp.gt.100)then
       print*,'**WARNING** bad convergence in int_prod_bessel'
-!        else
-!        print*,'kcp=',kcp
     endif
+    
     return
   endif
 
   if(a.eq.0.d0.and.b.ne.0.d0)then
+       
     if(n.ne.0)then
       int_prod_bessel=0.d0
       return
@@ -1963,16 +1988,21 @@ end
     int=0.d0
     done=.false.
     kcp=0
+
     do while (.not.done)
+        
       kcp=kcp+1
       int=int+coef_nk(m,q)*b**(m+2*q)*crochet(2*q+m+l,gam)
+      
       if(dabs(int-intold).lt.1d-15)then
         done=.true.
       else
         q=q+1
         intold=int
       endif
+    
     enddo
+
     int_prod_bessel=int*freal
     if(kcp.gt.100)stop '**WARNING** bad convergence in int_prod_bessel'
     return
@@ -1989,6 +2019,7 @@ end
     int=0.d0
     done=.false.
     kcp=0
+
     do while (.not.done)
       kcp=kcp+1
       int=int+coef_nk(n,q)*a**(n+2*q)*crochet(2*q+n+l,gam)
@@ -1999,9 +2030,11 @@ end
          intold=int
       endif
     enddo
+    
     int_prod_bessel=int*freal
     if(kcp.gt.100)stop '**WARNING** bad convergence in int_prod_bessel'
     return
+
   endif
 
   stop 'pb in int_prod_bessel!!'

tests/unit_test/unit_test.py

@@ -169,7 +169,7 @@ def run_hf(geo, basis, mult=1, pseudo=False, remove_after_sucess=True):
 
     ref_energy["sto-3g"]["methane"] = Energy(-39.7267433402, None)
     ref_energy["vdz"]["SO2"] = Energy(None, -41.48912297776174)
-    ref_energy["vdz"]["HBO"] = Energy(None, -19.1198251160)
+    ref_energy["vdz"]["HBO"] = Energy(None, -19.11982540413317)
 
     # ~#~#~#~#~#~#~#~#~#~#~#~#~#~#~ #
     # G l o b a l _ v a r i a b l e #