Bugfix: Added missing reset of potential at beginning of SCF iteration

The bug was introduced in commit 62285e99.

Thanks to Patrick for pointing out that there was a bug.

global/types.F90

@@ -922,6 +922,7 @@ MODULE m_types
      PROCEDURE :: init_potden_types
      PROCEDURE :: init_potden_simple
      GENERIC   :: init=>init_potden_types,init_potden_simple
+     PROCEDURE :: resetPotDen
   END TYPE t_potden
 CONTAINS
   SUBROUTINE usdus_init(ud,atoms,jsp)
@@ -1013,5 +1014,21 @@ CONTAINS
     pd%mmpMat = CMPLX(0.0,0.0)
   END SUBROUTINE init_potden_simple
 
+  SUBROUTINE resetPotDen(pd)
+
+    IMPLICIT NONE
+
+    CLASS(t_potden),INTENT(INOUT) :: pd
+
+    pd%pw=CMPLX(0.0,0.0)
+    pd%mt=0.0
+    pd%vacz=0.0
+    pd%vacxy=CMPLX(0.0,0.0)
+    pd%cdom = CMPLX(0.0,0.0)
+    pd%cdomvz = CMPLX(0.0,0.0)
+    pd%cdomvxy = CMPLX(0.0,0.0)
+    pd%mmpMat = CMPLX(0.0,0.0)
+  END SUBROUTINE resetPotDen
+
  
 END MODULE m_types

main/vgen.F90

@@ -123,6 +123,10 @@ CONTAINS
     !     units: hartrees
     !
 
+    CALL vTot%resetPotDen()
+    CALL vCoul%resetPotDen()
+    CALL vx%resetPotDen()
+
     ALLOCATE ( alphm(stars%ng2,2),excpw(stars%ng3),excxy(vacuum%nmzxyd,oneD%odi%n2d-1,2),&
          vbar(dimension%jspd),af1(3*stars%mx3),bf1(3*stars%mx3),xp(3,dimension%nspd),&
          vpw_exx(stars%ng3,dimension%jspd),vpw_wexx(stars%ng3,dimension%jspd),&