FUNCTION VERN26(E,IZZ)
C     ======================
C
C     Photoionization cross-sections for ground states
C       of all Fe ions.
C           Verner D.A. et al. 1996, ApJ 465
C           Verner & Yakovlev 1995, A&AS 109, 125
C
      INCLUDE 'IMPLIC.FOR'
      INCLUDE 'BASICS.FOR'
      PARAMETER (T18=1.D-18,MVER=26)
      DIMENSION S0(MVER),E0(MVER),EMX(MVER)
      DIMENSION Y0(MVER),Y1(MVER),YW(MVER),YA(MVER),PV(MVER)
      DIMENSION S95(MVER),E95(MVER),Y95(MVER),YW95(MVER),P95(MVER)
C
      DATA S0/3.062D-1,4.365D3,6.107D0,3.653D2,1.523D-3,5.259D-1,2.42D4,
     +        1.979D1,2.687D1,6.470D1,3.281D0,1.738D0,2.791D-3,1.454D-1,
     +        2.108D2,1.207D1,1.452D0,2.388D0,6.066D-5,4.455D-1,1.098D1,
     +        7.204D-2,2.580D4,1.276D1,1.195D1,8.099D1/
      DATA E0/0.05461,0.1761,0.1698,25.44,0.7256,2.656,5.059,0.07098,
     +        6.741,68.86,8.284,6.295,0.1317,0.8509,0.05555,28.73,
     +        0.3444,31.9,7.519D-4,20.11,9.243,9.713,45.75,73.26,
     +        1057.,293.2/
      DATA EMX/66.,76.17,87.05,106.7,128.8,152.7,178.3,205.5,921.1,
     +         959.,998.3,1039.,1081.,1125.,1181.,1216.,7651.,7769.,
     +         7918.,8041.,8184.,8350.,8484.,8638.,5.D4,5.D4/
      DATA Y0/1.382D2,9.272D1,1.76D2,0.,8.871D1,3.361D1,0.4546,2.542D3,
     +        2.494D1,1.19D-5,2.971D1,4.671D1,2.17D3,4.505D2,2.706D-4,
     +        0.,2.891D1,3.805D1,1.915D6,6.847D1,4.446D1,1.702D2,
     +        3.582D-2,0.,0.,0./
      DATA Y1/0.2481,1.075D2,1.847D1,0.,5.28D-2,3.743D-3,2.683D1,
     +        4.672D2,8.251,6.57D-3,0.522,0.1425,6.852D-3,2.504,
     +        1.628,0.,3.404,0.4805,3.14D1,3.989,3.512,4.263,8.712D-3,
     +        0.,0.,0./
      DATA YW/2.069D1,1.141D1,8.698,0.5602,5.064D1,1.558D1,2.516D-3,
     +        2.158D2,2.387D-4,2.778D-4,0.3279,0.3096,0.6938,0.4937,
     +        1.885D-3,0.,1.264,2.902D-2,4.398,2.757,1.748,9.551D-3,
     +        2.723D1,0.,0.,0./
      DATA YA/2.671D7,6.298D3,1.555D3,8.913D0,3.736D1,1.450D1,4.850D4,
     +        1.745D4,1.807D2,2.062D1,5.360D1,1.130D2,2.487D3,1.239D3,
     +        2.045D4,5.150D2,3.960D2,2.186D1,1.606D6,4.236D1,7.637D1,
     +        1.853D2,1.358D0,4.914D1,5.769D1,3.288D1/
      DATA PV/7.923,5.204,8.055,6.538,17.67,16.32,2.374,6.75,6.29,
     +        4.111,8.571,8.037,9.791,8.066,6.033,3.846,10.13,9.589,
     +        8.813,9.724,7.962,8.843,26.04,4.941,1.718,2.963/
      DATA S95/6.298D1,4.624D1,4.422D1,4.81D1,5.143D1,5.246D1,5.21D1,
     +         5.336D1,2.205D2,2.392D2,2.449D2,3.325D2,3.316D2,3.367D2,
     +         1.496D2,3.383D2,1.15D1,8.327D0,1.155D1,8.619D0,8.773D0,
     +         1.181D1,9.098D1,1.157D1,1.195D1,8.099D1/
      DATA E95/76.3,77.5,77.77,76.25,72.73,72.6,74.33,75.56,171.5,
     +         164.7,163.2,138.3,139.2,138.7,213.6,139.6,1067.,1249.,
     +         1068.,1235.,1228.,1066.,1215.,1087.,1057.,293.2/
      DATA Y95/1.479D1,2.155D1,2.336D1,2.286D1,2.428D1,2.751D1,3.306D1,
     +         3.855D1,5.298D1,5.276D1,5.452D1,5.09D1,5.237D1,5.279D1,
     +         7.000D1,5.459D1,3.412D1,5.000D1,3.578D1,5.000D1,5.000D1,
     +         4.116D1,5.000D1,5.086D1,5.769D1,3.288D1/
      DATA YW95/0.2646,0.2599,0.2557,0.2449,0.1365,0.02105,0.02404,
     +          0.02667,1.508D-5,1.574D-5,1.594D-4,1.114D-5,1.107D-5,
     +          1.111D-5,0.1,1.179D-5,10*0./ 
      DATA P95/7.672,7.138,7.017,7.043,7.028,6.823,6.509,6.265,4.154,
     +         4.204,4.187,4.446,4.41,4.407,3.7,4.366,1.922,1.65,1.895,
     +         1.65,1.65,1.827,1.65,1.722,1.718,2.963/
C
      VERN26=0.
      IVER=IZZ
C
C     1996 Expression
C
      IF(E.LT.EMX(IVER)) THEN
        XX=E/E0(IVER)-Y0(IVER)
        YY=SQRT(XX*XX+Y1(IVER)*Y1(IVER))
        AA=(XX-UN)*(XX-UN)+YW(IVER)*YW(IVER)
        BB=YY**(HALF*PV(IVER)-5.5)
        CC=(UN+SQRT(YY/YA(IVER)))**PV(IVER)
        FY=AA*BB/CC
        VERN26=S0(IVER)*T18*FY
      ELSE
C
C     1995 Expression for high energies
C          (ionization of inner shell electron)
C
        YY=E/E95(IVER)
        XL=0.
        IF(IZZ.LE.16) XL=UN
        Q=HALF*P95(IVER)-5.5-XL
        AA=(YY-UN)*(YY-UN)+YW95(IVER)*YW95(IVER)
        BB=YY**Q
        CC=(UN+SQRT(YY/Y95(IVER)))**P95(IVER)
        FY=AA*BB/CC
        VERN26=S95(IVER)*T18*FY
      END IF
C
      RETURN
      END