60 lines
1.6 KiB
Fortran
60 lines
1.6 KiB
Fortran
FUNCTION CKOEST(S,L,N,FREQ,GG)
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C ==============================
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C
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C EVALUATES HE I PHOTOIONIZATION CROSS SECTION USING
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C KOESTER'S FITS (1985, AA 149, 423)
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C
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C CALLING SEQUENCE INCLUDES:
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C S = MULTIPLICITY, EITHER 1 OR 3
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C L = ANGULAR MOMENTUM, 0, 1, OR 2;
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C for L > 2 - hydrogenic expresion
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C N = PRINCIPAL QUANTUM NUMBER
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C FREQ = FREQUENCY
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C GG = STATISTICAL WEIGHT
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C
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INCLUDE 'IMPLIC.FOR'
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INCLUDE 'BASICS.FOR'
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INTEGER S,L,SS,LL
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PARAMETER (PHOT0=2.815D29)
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DIMENSION COEF(3,11),IST(3)
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C
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DATA IST/1,2,6/
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C
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DATA COEF/
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. -58.229, 4.3965, -0.22134 ,
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. -68.438, 5.7453, -0.26277 ,
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. -67.310, 6.1831, -0.32244 ,
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. -92.020, 10.313 , -0.45090 ,
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. -68.936, 5.2666, -0.15812 ,
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. -63.408, 3.8797, -0.12479 ,
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. -63.778, 4.5102, -0.18213 ,
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. -76.903, 6.3639, -0.21565 ,
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. -61.027, 3.1833, -0.043675,
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. -83.287, 7.1751, -0.20821 ,
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. -83.287, 7.1751, -0.20821 /
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C
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SAVE COEF,IST
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C
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IF(L.GT.2) GO TO 20
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C
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C SELECT BEGINNING AND END OF COEFFICIENTS
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C
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SS=(S-1)/2
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LL=2*L
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NSL=IST(N)+LL+SS
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C
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C EVALUATE CROSS SECTION
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C
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X=LOG(CAS/FREQ)
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CKOEST=EXP(COEF(1,NSL)+X*(COEF(2,NSL)+X*COEF(3,NSL)))/GG
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RETURN
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C
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C Hydrogenic expression for L > 2
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C [multiplied by relative population of state (s,l,n), ie.
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C by stat.weight(s,l)/stat.weight(n)]
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C
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20 GN=TWO*N*N
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CKOEST=PHOT0/FREQ/FREQ/FREQ/N**5*(2*L+1)*S/GN
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RETURN
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END
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