42 lines
1.0 KiB
Fortran
42 lines
1.0 KiB
Fortran
function wn(xn,a,ane,z)
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c
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c evaluation of the occupation probablities for a hydrogenic ion
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c using eqs (4.26), and (4.39) of Hummer,Mihalas Ap.J. 331, 794, 1988.
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c approximate evaluation of Q(beta) - Hummer
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c
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c Input: xn - real number corresponding to quantum number n
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c a - correlation parameter
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c ane - electron density
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c z - ionic charge
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c
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INCLUDE 'IMPLIC.FOR'
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INCLUDE 'BASICS.FOR'
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parameter (p1=0.1402,p2=0.1285,p3=un,p4=3.15,p5=4.)
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parameter (tkn=3.01,ckn=5.33333333,cb0=8.59d14)
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parameter (f23=-2./3.)
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c
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cb=cb0*bergfc
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c
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c evaluation of k(n)
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c
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if(xn.le.tkn) then
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xkn=un
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else
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xn1=un/(xn+un)
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xkn=ckn*xn*xn1*xn1
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end if
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c
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c evaluation of beta
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c
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beta=cb*z*z*z*xkn/(xn*xn*xn*xn)*exp(f23*log(ane))
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c
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c approximate expression for Q(beta)
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c
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x=exp(p4*log(un+p3*a))
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c1=p1*(x+p5*(z-un)*a*a*a)
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c2=p2*x
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f=(c1*beta*beta*beta)/(un+c2*beta*sqrt(beta))
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wn=f/(un+f)
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return
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end
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