vxcpw91.f 5.7 KB
Newer Older
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229
      MODULE m_vxcpw91
      CONTAINS
c.....-----------------------------------------------------------------
c.....pw91 exchange-correlation potential in hartree.
c.....------------------------------------------------------------------
      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.eq.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

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

        ro=rou+rod

        if(ro.le.smlc) go to 200

        zta=(rou-rod)/ro
        if(zta.gt.1.e0-sml) zta = 1.e0 - sml
        if(zta.lt.-1.e0-sml) zta = -1.e0 + sml

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


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

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

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

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

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

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

c         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


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

          sd = 0.128278244e0*agrd(i)/rod43

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

c         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


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


c         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


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


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

  300 continue

      END SUBROUTINE vxcpw91
      END MODULE m_vxcpw91