c----------------------------------------------------------------------
      	subroutine CORPW91(RS,ZET,G,EC,ECRS,ECZET,T,UU,VV,WW,H,
     1                   DVCUP,DVCDN)
c  pw91 CORRELATION, modified by K. Burke to put all arguments 
c  as variables in calling statement, rather than in common block
c
c  author: modified by K. Burke, 10.18.99
c      in: RS  - SEITZ RADIUS
c          ZET - RELATIVE SPIN POLARIZATION
c          T   - ABS(GRAD D)/(D*2.*KS*G)
c          UU  - (GRAD D)*GRAD(ABS(GRAD D))/(D**2 * (2*KS*G)**3)
c          VV  - (LAPLACIAN D)/(D * (2*KS*G)**2)
c          WW  -  (GRAD D)*(GRAD ZET)/(D * (2*KS*G)**2
c     out: H - NONLOCAL PART OF CORRELATION ENERGY PER ELECTRON
c          DVCUP,DVCDN - NONLOCAL PARTS OF CORRELATION POTENTIALS
c   calls: --
      IMPLICIT REAL*8 (A-H,O-Z)
      parameter(xnu=15.75592D0,cc0=0.004235D0,cx=-0.001667212D0)
      parameter(alf=0.09D0)
      parameter(c1=0.002568D0,c2=0.023266D0,c3=7.389D-6,c4=8.723D0)
      parameter(c5=0.472D0,c6=7.389D-2,a4=100.D0)
      parameter(thrdm=-0.333333333333D0,thrd2=0.666666666667D0)