FUNCTION HEPHOT(S,L,N,FREQ) C =========================== C C EVALUATES HE I PHOTOIONIZATION CROSS SECTION USING SEATON C FERNLEY'S CUBIC FITS TO THE OPACITY PROJECT CROSS SECTIONS C UP TO SOME ENERGY "EFITM" IN THE RESONANCE-FREE ZONE. BEYOND C THIS ENERGY LINEAR FITS TO LOG SIGMA IN LOG (E/E0) ARE USED. C THIS EXTRAPOLATION SHOULD BE USED UP TO THE BEGINNING OF THE C RESONANCE ZONE "XMAX", BUT AT PRESENT IT IS USED THROUGH IT. C BY CHANGING A FEW LINES THAT ARE PRESENTLY COMMENTED OUT, C FOR ENERGIES IN THE RESONANCE ZONE A VALUE OF 1/100 OF THE C THRESHOLD CROSS SECTION IS USED -- THIS IS PURELY AD HOC AND C ONLY A TEMPORARY MEASURE. OBVIOUSLY ANY OTHER VALUE OR FUNCTIONAL C FORM CAN BE INSERTED HERE. C C CALLING SEQUENCE INCLUDES: C S = MULTIPLICITY, EITHER 1 OR 3 C L = ANGULAR MOMENTUM, 0, 1, OR 2; C for L > 2 - hydrogenic expresion C FREQ = FREQUENCY C C DGH JUNE 1988 JILA, slightly modified by I.H. C INCLUDE 'PARAMS.FOR' INTEGER S,L,SS,LL DIMENSION COEF(4,53),IST(3,2),N0(3,2), * FL0(53),A(53),B(53),XFITM(53) c DIMENSION XMAX(53) C DATA IST/1,36,20,11,45,28/ DATA N0/1,2,3,2,2,3/ C DATA FL0/ . 2.521D-01,-5.381D-01,-9.139D-01,-1.175D+00,-1.375D+00,-1.537D+00, .-1.674D+00,-1.792D+00,-1.896D+00,-1.989D+00,-4.555D-01,-8.622D-01, .-1.137D+00,-1.345D+00,-1.512D+00,-1.653D+00,-1.774D+00,-1.880D+00, .-1.974D+00,-9.538D-01,-1.204D+00,-1.398D+00,-1.556D+00,-1.690D+00, .-1.806D+00,-1.909D+00,-2.000D+00,-9.537D-01,-1.204D+00,-1.398D+00, .-1.556D+00,-1.690D+00,-1.806D+00,-1.909D+00,-2.000D+00,-6.065D-01, .-9.578D-01,-1.207D+00,-1.400D+00,-1.558D+00,-1.692D+00,-1.808D+00, .-1.910D+00,-2.002D+00,-5.749D-01,-9.352D-01,-1.190D+00,-1.386D+00, .-1.547D+00,-1.682D+00,-1.799D+00,-1.902D+00,-1.995D+00/ C DATA XFITM/ . 3.262D-01, 6.135D-01, 9.233D-01, 8.438D-01, 1.020D+00, 1.169D+00, . 1.298D+00, 1.411D+00, 1.512D+00, 1.602D+00, 7.228D-01, 1.076D+00, . 1.206D+00, 1.404D+00, 1.481D+00, 1.464D+00, 1.581D+00, 1.685D+00, . 1.777D+00, 9.586D-01, 1.187D+00, 1.371D+00, 1.524D+00, 1.740D+00, . 1.854D+00, 1.955D+00, 2.046D+00, 9.585D-01, 1.041D+00, 1.371D+00, . 1.608D+00, 1.739D+00, 1.768D+00, 1.869D+00, 1.803D+00, 7.360D-01, . 1.041D+00, 1.272D+00, 1.457D+00, 1.611D+00, 1.741D+00, 1.855D+00, . 1.870D+00, 1.804D+00, 9.302D-01, 1.144D+00, 1.028D+00, 1.210D+00, . 1.362D+00, 1.646D+00, 1.761D+00, 1.863D+00, 1.954D+00/ C DATA A/ . 6.95319D-01, 1.13101D+00, 1.36313D+00, 1.51684D+00, 1.64767D+00, . 1.75643D+00, 1.84458D+00, 1.87243D+00, 1.85628D+00, 1.90889D+00, . 9.01802D-01, 1.25389D+00, 1.39033D+00, 1.55226D+00, 1.60658D+00, . 1.65930D+00, 1.68855D+00, 1.62477D+00, 1.66726D+00, 1.83599D+00, . 2.50403D+00, 3.08564D+00, 3.56545D+00, 4.25922D+00, 4.61346D+00, . 4.91417D+00, 5.19211D+00, 1.74181D+00, 2.25756D+00, 2.95625D+00, . 3.65899D+00, 4.04397D+00, 4.13410D+00, 4.43538D+00, 4.19583D+00, . 1.79027D+00, 2.23543D+00, 2.63942D+00, 3.02461D+00, 3.35018D+00, . 3.62067D+00, 3.85218D+00, 3.76689D+00, 3.49318D+00, 1.16294D+00, . 1.86467D+00, 2.02110D+00, 2.24231D+00, 2.44240D+00, 2.76594D+00, . 2.93230D+00, 3.08109D+00, 3.21069D+00/ C DATA B/ .-1.29000D+00,-2.15771D+00,-2.13263D+00,-2.10272D+00,-2.10861D+00, .-2.11507D+00,-2.11710D+00,-2.08531D+00,-2.03296D+00,-2.03441D+00, .-1.85905D+00,-2.04057D+00,-2.02189D+00,-2.05930D+00,-2.03403D+00, .-2.02071D+00,-1.99956D+00,-1.92851D+00,-1.92905D+00,-4.58608D+00, .-4.40022D+00,-4.39154D+00,-4.39676D+00,-4.57631D+00,-4.57120D+00, .-4.56188D+00,-4.55915D+00,-4.41218D+00,-4.12940D+00,-4.24401D+00, .-4.40783D+00,-4.39930D+00,-4.25981D+00,-4.26804D+00,-4.00419D+00, .-4.47251D+00,-3.87960D+00,-3.71668D+00,-3.68461D+00,-3.67173D+00, .-3.65991D+00,-3.64968D+00,-3.48666D+00,-3.23985D+00,-2.95758D+00, .-3.07110D+00,-2.87157D+00,-2.83137D+00,-2.82132D+00,-2.91084D+00, .-2.91159D+00,-2.91336D+00,-2.91296D+00/ C DATA ((COEF(I,J),I=1,4),J=1,10)/ . 8.734D-01,-1.545D+00,-1.093D+00, 5.918D-01, 9.771D-01,-1.567D+00, .-4.739D-01,-1.302D-01, 1.174D+00,-1.638D+00,-2.831D-01,-3.281D-02, . 1.324D+00,-1.692D+00,-2.916D-01, 9.027D-02, 1.445D+00,-1.761D+00, .-1.902D-01, 4.401D-02, 1.546D+00,-1.817D+00,-1.278D-01, 2.293D-02, . 1.635D+00,-1.864D+00,-8.252D-02, 9.854D-03, 1.712D+00,-1.903D+00, .-5.206D-02, 2.892D-03, 1.782D+00,-1.936D+00,-2.952D-02,-1.405D-03, . 1.845D+00,-1.964D+00,-1.152D-02,-4.487D-03/ DATA ((COEF(I,J),I=1,4),J=11,19)/ . 7.377D-01,-9.327D-01,-1.466D+00, 6.891D-01, 9.031D-01,-1.157D+00, .-7.151D-01, 1.832D-01, 1.031D+00,-1.313D+00,-4.517D-01, 9.207D-02, . 1.135D+00,-1.441D+00,-2.724D-01, 3.105D-02, 1.225D+00,-1.536D+00, .-1.725D-01, 7.191D-03, 1.302D+00,-1.602D+00,-1.300D-01, 7.345D-03, . 1.372D+00,-1.664D+00,-8.204D-02,-1.643D-03, 1.434D+00,-1.715D+00, .-4.646D-02,-7.456D-03, 1.491D+00,-1.760D+00,-1.838D-02,-1.152D-02/ DATA ((COEF(I,J),I=1,4),J=20,27)/ . 1.258D+00,-3.442D+00,-4.731D-01,-9.522D-02, 1.553D+00,-2.781D+00, .-6.841D-01,-4.083D-03, 1.727D+00,-2.494D+00,-5.785D-01,-6.015D-02, . 1.853D+00,-2.347D+00,-4.611D-01,-9.615D-02, 1.955D+00,-2.273D+00, .-3.457D-01,-1.245D-01, 2.041D+00,-2.226D+00,-2.669D-01,-1.344D-01, . 2.115D+00,-2.200D+00,-1.999D-01,-1.410D-01, 2.182D+00,-2.188D+00, .-1.405D-01,-1.460D-01/ DATA ((COEF(I,J),I=1,4),J=28,35)/ . 1.267D+00,-3.417D+00,-5.038D-01,-1.797D-02, 1.565D+00,-2.781D+00, .-6.497D-01,-5.979D-03, 1.741D+00,-2.479D+00,-6.099D-01,-2.227D-02, . 1.870D+00,-2.336D+00,-4.899D-01,-6.616D-02, 1.973D+00,-2.253D+00, .-3.972D-01,-8.729D-02, 2.061D+00,-2.212D+00,-3.072D-01,-1.060D-01, . 2.137D+00,-2.189D+00,-2.352D-01,-1.171D-01, 2.205D+00,-2.186D+00, .-1.621D-01,-1.296D-01/ DATA ((COEF(I,J),I=1,4),J=36,44)/ . 1.129D+00,-3.149D+00,-1.910D-01,-5.244D-01, 1.431D+00,-2.511D+00, .-3.710D-01,-1.933D-01, 1.620D+00,-2.303D+00,-3.045D-01,-1.391D-01, . 1.763D+00,-2.235D+00,-1.829D-01,-1.491D-01, 1.879D+00,-2.215D+00, .-9.003D-02,-1.537D-01, 1.978D+00,-2.213D+00,-2.066D-02,-1.541D-01, . 2.064D+00,-2.220D+00, 3.258D-02,-1.527D-01, 2.140D+00,-2.225D+00, . 6.311D-02,-1.455D-01, 2.208D+00,-2.229D+00, 7.977D-02,-1.357D-01/ DATA ((COEF(I,J),I=1,4),J=45,53)/ . 1.204D+00,-2.809D+00,-3.094D-01, 1.100D-01, 1.455D+00,-2.254D+00, .-4.795D-01, 6.872D-02, 1.619D+00,-2.109D+00,-3.357D-01,-2.532D-02, . 1.747D+00,-2.065D+00,-2.317D-01,-5.224D-02, 1.853D+00,-2.058D+00, .-1.517D-01,-6.647D-02, 1.943D+00,-2.055D+00,-1.158D-01,-6.081D-02, . 2.023D+00,-2.070D+00,-6.470D-02,-6.800D-02, 2.095D+00,-2.088D+00, .-2.357D-02,-7.250D-02, 2.160D+00,-2.107D+00, 1.065D-02,-7.542D-02/ C IF(L.GT.2) GO TO 20 C C SELECT BEGINNING AND END OF COEFFICIENTS C SS=(S+1)/2 LL=L+1 NSL0=N0(LL,SS) I=IST(LL,SS)+N-NSL0 C C EVALUATE CROSS SECTION C FL=LOG10(FREQ/3.28805E15) X=FL-FL0(I) IF(X.GE.-0.001D0) THEN IF(X.LT.XFITM(I)) THEN P=COEF(4,I) DO 10 K=1,3 P=X*P+COEF(4-K,I) 10 CONTINUE HEPHOT=1.D-18*1.D1**P ELSE C OTHERWISE REMOVE INSTRUCTION AND 3 FOLLOWING "C" C ELSE IF(X.LT.XMAX(I)) THEN HEPHOT=1.D-18*1.D1**(A(I)+B(I)*X) C ELSE C HEPHOT=1.D-18*1.D1**(COEF(1,I)-2.0D0) END IF ELSE HEPHOT=0. END IF RETURN C C Hydrogenic expression for L > 2 C [multiplied by relative population of state (s,l,n), ie. C by stat.weight(s,l)/stat.weight(n)] C 20 GN=2.D0*N*N HEPHOT=2.815D29/FREQ/FREQ/FREQ/N**5*(2*L+1)*S/GN RETURN END