hdf5_obj_CreateGroup Subroutine

    impure subroutine hdf5_obj_CreateGroup(this,groupname)
      !> Creates a group (analogous to directory) in an HDF5
      ! file and updates hash table.
      implicit none
      class(hdf5_obj),  intent(inout) :: this                                  !! A HDF5 object
      character(len=*), intent(in)    :: groupname                             !! Group name
      ! Work variables
      integer             :: ierr
      integer(HID_T)      :: gid
      character(len=:), &
              allocatable :: groupname_

      ! Format name of this group
      groupname_=this%FixGroupName(groupname)

      ! Create a group in the HDF5 file
      call H5Gcreate_f(this%fid,groupname_,gid,ierr)
      if (ierr.ne.0) &
        call this%parallel%Stop("Unable to create a group in HDF5 file "//this%filename)

      ! Add to hash table
      call this%tbl%Put(key=this%tbl%HashString(groupname_),val=gid)

      ! Close group we just created
      call this%CloseGroup(groupname)

      return
    end subroutine hdf5_obj_CreateGroup