vxcpw91.f90 6.09 KB
Newer Older
Matthias Redies's avatar
Matthias Redies committed
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221
MODULE m_vxcpw91
CONTAINS
!.....-----------------------------------------------------------------
!.....pw91 exchange-correlation potential in hartree.
!.....------------------------------------------------------------------
   SUBROUTINE vxcpw91( &
      jspins,mirm,irmx,rh,agr,agru,agrd, &
      g2r,g2ru,g2rd,gggr,gggru,gggrd,gzgr, &
      vx,vxc, &
      idsprs,isprsv,sprsv)

      USE m_corl91
      USE m_corg91
      USE m_xch91
      USE m_constants, ONLY: pi_const

      IMPLICIT NONE

! .. Arguments ..
      INTEGER, INTENT (IN) :: jspins,irmx,mirm,isprsv,idsprs
      REAL,    INTENT (IN) :: sprsv

      REAL,    INTENT (IN) :: rh(mirm,jspins)
      REAL,    INTENT (IN) :: agr(mirm),agru(mirm),agrd(mirm)
      REAL,    INTENT (IN) :: g2r(mirm),g2ru(mirm),g2rd(mirm)
      REAL,    INTENT (IN) :: gggr(mirm),gggru(mirm)
      REAL,    INTENT (IN) :: gggrd(mirm),gzgr(mirm)
      REAL,    INTENT (OUT):: vx(mirm,jspins),vxc(mirm,jspins)

! .. local variables
      REAL :: ro,zta,alf,alfc,c13,c23,c43,c53, &
              cedg,cedl,dbrod,dbrou,dsprs,ec,ecrs,eczta,fk,gz, &
              ro13,ro2,rod,rod3,rod43,rod53,rou,rou3,rou43,rou53, &
              rs,sd,sk,su,tc,td,tksg,tu,uc,ud,uu,vc, &
              vcgd,vcgu,vcld,vclu,vxgd,vxgu,vxld, &
              vxlu,wc,xced,xedg,xedgd,xedgu,xedl,xedld,xedlu, &
              rou13,rod13,xcptu,xcptd

      INTEGER :: i
      REAL, PARAMETER :: sml = 1.e-14
      REAL, PARAMETER :: smlc = 2.01e-14

      DO 300 i = 1,irmx

         IF (jspins == 1) THEN
            rou=rh(i,1)/2
            rou=max(rou,sml)
            rod=rou
         ELSE
            rou=rh(i,1)
            rod=rh(i,jspins)
            rou=max(rou,sml)
            rod=max(rod,sml)
         ENDIF

         !.....
         !       vxlu,vxld,vxgu,vxgd: exchange potential in ry.(local,grad),
         !c        (up,dw).
         !       vclu,vcld,vcgu,vcgd: correl. potential in ry.(local,grad),
         !c        (up,dw).
         !       all later in hartree.
         !.....
         vxlu = 0.0e0
         vclu = 0.0e0
         vxld = 0.0e0
         vcld = 0.0e0
         vxgu = 0.0e0
         vcgu = 0.0e0
         vxgd = 0.0e0
         vcgd = 0.0e0
         !.....

         ro=rou+rod

         if(ro <= smlc) go to 200

         zta=(rou-rod)/ro
         if(zta > 1.e0-sml) zta = 1.e0 - sml
         if(zta < -1.e0-sml) zta = -1.e0 + sml

         !.....
         c13 = 1.e0/3.e0
         c23 = 2.e0/3.e0
         c43 = 4.e0/3.e0
         c53 = 5.e0/3.e0

         !.....    alf=-3*(3/4*pai)**(1/3).
         alf = -1.861051473e0
         !.....
         ro2 = ro*ro
         ro13 = ro**c13
         !.....
         rou3 = rou**3
         rou13 = rou**c13
         rou43 = rou**c43
         !.....
         rod3 = rod**3
         rod13 = rod**c13
         rod43 = rod**c43
         !.....
         !       gr2=drr*drr
         !       gr2u=drru**2
         !       drrd=drr-drru
         !       gr2d=drrd**2
         !       ddrrd=ddrr-ddrru
         !.....
         !.....  gz,gz2,gz3: for wang-perdew ssf.
         gz = ((1.e0+zta)**c23+ (1.e0-zta)**c23)/2.e0
         !.....
         !.....
         rs = 0.620350491e0/ro13
         !.....
         !.....  exchange-potential, vxp,vxlu,vxld: v-exchange-(para,up,dw).
         vxlu = c43*alf*rou13
         vxld = c43*alf*rod13

         !.....
         !....  .gradient correction.
         !.....
         !         if(abs(agr(i)).lt.sml) go to 200
         !.....

         !.....
         dsprs = 1.e0
         if(idsprs == 1) dsprs = 1.e-19
         if(isprsv == 1) dsprs = dsprs*sprsv

         !.....
         !      agr,agru,agrd: abs(grad(rho)), for all, up, and down.
         !c     gr2,gr2u,gr2d: grad(rho_all)**2, grad(rho_up)**2, grad(rho_d)**2.
         !      g2r,g2ru,g2rd: laplacian rho_all, _up and _down.
         !      gggru,-d: grad(rho)*grad(abs(grad(rho))) for all,up and down.
         !      grgru,-d: grad(rho_all)*grad(rhor_up) and for down.

         !         g2r=ddrr+2*drr/rv
         !.....
         rou53 = rou**c53
         !.....
         !.....  edrru: d(abs(d(rou)/dr))/dr, edrrd for down.
         !         edrru=ddrru
         !         if(drru.lt.0.) edrru=-ddrru
         !.....
         !         agr,agbru,-d: abs(grad(rho)),for rou, rod.
         !         gggru,-d: grad(rho)*grad(abs(grad(rho))) for up and down.
         !.....  su:at ro=2*rou. 1/(2(3*pai**2)**(1/3))*|grad(rou)|/rou**(4/3).
         su = 0.128278244e0*agru(i)/rou43

         !         if(su.gt.huges) go to 200

         !         g2ru=ddrru+2*drru/rv

         tu = .016455307e0*g2ru(i)/rou53
         uu = 0.002110857e0*gggru(i)/rou3

         dbrou = rou*2

         call xch91(dbrou,su,uu,tu,xedlu,xedgu,vxlu,vxgu)

         vxgu = dsprs*vxgu

         !.....
         rod53 = rod**c53
         !         edrrd=ddrrd
         !         if(drrd.lt.0.) edrrd=-ddrrd

         sd = 0.128278244e0*agrd(i)/rod43

         !         if(sd.gt.huges) go to 200

         !         g2rd=ddrrd+2*drrd/rv

         td = .016455307e0*g2rd(i)/rod53
         ud = 0.002110857e0*gggrd(i)/rod3

         dbrod = rod*2

         call xch91(dbrod,sd,ud,td,xedld,xedgd,vxld,vxgd)

         vxgd = dsprs*vxgd

         !....   cro: c(n) of (6),phys.rev..b33,8822('86). in ry.
         !....   dcdr: d(cro)/d(ro).
         !.....  0.001625816=1.745*f(=0.11)*cro(rs=0).

         !         pw91

         call corl91(rs,zta,ec,vclu,vcld,ecrs,eczta,alfc)

         vclu = vclu*2.e0
         vcld = vcld*2.e0

         fk = 1.91915829e0/rs
         sk = sqrt(4.e0*fk/pi_const)
         tksg = 2.e0*sk*gz
         tc = agr(i)/ (ro*tksg)
         uc = gggr(i)/ (ro2*tksg**3)
         vc = g2r(i)/ (ro*tksg**2)
         wc = gzgr(i)/ (ro*tksg**2)

         call corg91(fk,sk,gz,ec,ecrs,eczta,rs,zta,tc,uc,vc,wc,cedg, &
                     vcgu,vcgd)

         vcgu = dsprs*vcgu*2.e0
         vcgd = dsprs*vcgd*2.e0

200      continue

         xcptu = vxlu + vclu + vxgu + vcgu
         xcptd = vxld + vcld + vxgd + vcgd

         !     in Ry.
         vx(i,1)       = vxlu + vxgu
         vx(i,jspins)  = vxld + vxgd

         vxc(i,1)      = xcptu
         vxc(i,jspins) = xcptd

300   END DO

   END SUBROUTINE vxcpw91
END MODULE m_vxcpw91