subroutine init_cc_hash(hash_table, hash_table_size)
! routine to setup the hash for the quadrupels
type(cc_hash), pointer, intent(inout) :: hash_table(:)
integer, intent(in) :: hash_table_size
integer :: i
! estimate the hash table size with num_doubles^2 for now..
! although this number can be reduced substantially i guess
allocate(hash_table(hash_table_size))
do i = 1, hash_table_size
hash_table(i)%found = .false.
hash_table(i)%amp = 0.0_dp
nullify (hash_table(i)%next)
end do
end subroutine init_cc_hash