转自：http://bbs.keinsci.com/thread-9494-1-6.html

      SUBROUTINE CONSTR_CELL_RELAX(FCELL)

      USE prec

      REAL(q) FCELL(3,3)

      DO I=1,3

        FCELL(3,I)=0

        FCELL(I,3)=0

      ENDDO

!     just one simple example

!     relaxation in x directions only

!      SAVE=FCELL(1,1)

!      FCELL=0   ! F90 style: set the whole array to zero

!      FCELL(1,1)=SAVE

!     relaxation in z direction only

!      SAVE=FCELL(3,3)

!      FCELL=0   ! F90 style: set the whole array to zero

!      FCELL(3,3)=SAVE

      RETURN

      END SUBROUTINE