c----------------------------------------------------------------------
      subroutine EASYPBE(up,agrup,delgrup,uplap,dn,agrdn,delgrdn,dnlap,
c is a driver for the PBE subroutines, using simple inputs
c
     1           agr,delgr,lcor,lpot,
     1           exlsd,vxuplsd,vxdnlsd,eclsd,vcuplsd,vcdnlsd,
     1           expw91,vxuppw91,vxdnpw91,ecpw91,vcuppw91,vcdnpw91,
     1           expbe,vxuppbe,vxdnpbe,ecpbe,vcuppbe,vcdnpbe,
     1		 exb,vxupb,vxdnb,eclyp,vcuplyp,vcdum)
c  author: K. Burke, May 14, 1996, modified April 7, 
c          to include Becke 88 exchange and LYP correlation
c WARNING: LYP for spin-unpolarized only
c      in: up - up density
c	   agrup - |grad up|
c	   delgrup - (grad up).(grad |grad up|) 
c          uplap - grad^2 
c          up - Laplacian of up
c          dn,agrdn,delgrdn,dnlap - corresponding down quantities
c          agr - |grad rho|
c          delgr - (grad rho).(grad |grad rho|) 
c          lcor - flag to do correlation(=0=>don't)
c          lpot - flag to do potential(=0=>don't)
c     out: exlsd - LSD exchange energy density, so that
c	   ExLSD - int d^3r rho(r) exlsd(r)
c	   vxuplsd - up LSD exchange potential
c	   vxdnlsd - down LSD exchange potential
c          exclsd - LSD exchange-correlation energy density
c	   vxcuplsd - up LSD exchange-correlation potential
c	   vxcdnlsd - down LSD exchange-correlation potential
c          expw91,vxuppw91,vxdnpw91,ecpw91,etc.=PW91 quantities
c          expbe,vxuppbe,vxdnpbe,ecpbe,etc.=PBE quantities
c          exb,vxupb,vxdnb,eclyp,etc.=BLYP quantities
c calls: EXCHPBE, EXCH, CORPBE2, CORLSD, CORPW91, LYP
c
c needed constants: pi32=3 pi**2
c                   alpha=(9pi/4)**thrd
      implicit real*8(a-h,o-z)
      parameter(thrd=1.d0/3.d0,thrd2=2.d0*thrd)
      parameter(pi32=29.608813203268075856503472999628d0)
      parameter(pi=3.1415926535897932384626433832795d0)
      parameter(alpha=1.91915829267751300662482032624669d0)
c----------------------------------------------------------------------
c PBE exchange
c use  Ex[up,dn]=0.5*(Ex[2*up]+Ex[2*dn]) (i.e., exact spin-scaling)
c do up exchange
c fk=local Fermi wavevector for 2*up=(3 pi^2 (2up))^(1/3) 
c s=dimensionless density gradient=|grad rho|/ (2*fk*rho)_(rho=2*up)
c u=delgrad/(rho^2*(2*fk)**3)_(rho=2*up)
c v=Laplacian/(rho*(2*fk)**2)_(rho=2*up)