211 lines
5.5 KiB
Fortran
211 lines
5.5 KiB
Fortran
SUBROUTINE ELDENS(ID,T,AN,ANE)
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C ==============================
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C
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C Evaluation of the electron density and the total hydrogen
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C number density for a given total particle number density
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C and temperature;
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C by solving the set of Saha equations, charge conservation and
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C particle conservation equations (by a Newton-Raphson method)
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C
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C Input parameters:
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C T - temperature
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C AN - total particle number density
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C
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C Output:
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C ANE - electron density
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C ANP - proton number density
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C AHTOT - total hydrogen number density
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C AHMOL - relativer number of hydrogen molecules with respect to the
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C total number of hydrogens
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C ENERG - part of the internal energy: excitation and ionization
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C
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INCLUDE 'PARAMS.FOR'
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INCLUDE 'MODELP.FOR'
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common/hydmol/anhmi,ahmol
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common/hydato/ah,anh,anp
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common/nerela/anerel
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parameter (un=1.d0,two=2.d0,half=0.5d0)
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DIMENSION R(3,3),S(3),P(3)
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C
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TK=BOLK*T
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if(ifmol.gt.0.and.t.lt.tmolim) then
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aein=an*anerel
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call moleq(id,t,an,aein,ane,0)
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anerel=ane/an
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return
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end if
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c
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QM=0.
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Q2=0.
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QP=0.
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Q=0.
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DQN=0.
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TK=BOLK*T
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THET=5.0404D3/T
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C
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C Coefficients entering ionization (dissociation) balance of:
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C atomic hydrogen - QH;
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C negative hydrogen ion - QM
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C hydrogen molecule - Q2
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C ion of hydrogen molecule - QP
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C
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IF(IATREF.EQ.IATH) THEN
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QM=1.0353D-16/T/SQRT(T)*EXP(8762.9/T)
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QH0=EXP((15.38287+1.5*LOG10(T)-13.595*THET)*2.30258509299405)
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c
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if(t.gt.16000.) then
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ih2=0
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else
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ih2=1
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QP=TK*EXP((-11.206998+THET*(2.7942767+THET*
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* (0.079196803-0.024790744*THET)))*2.30258509299405)
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Q2=TK*EXP((-12.533505+THET*(4.9251644+THET*
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* (-0.056191273+0.0032687661*THET)))*2.30258509299405)
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end if
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END IF
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C
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C Initial estimate of the electron density
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C
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if(anerel.le.0.) then
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if(t.gt.1.e4) then
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anerel=0.5
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else
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if(elec(id).gt.0..and.dens(id).gt.0.) then
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anerel=elec(id)/(elec(id)+dens(id)/wmm(id))
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else
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anerel=0.1
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end if
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end if
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end if
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c
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ANE=AN*ANEREL
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IT=0
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C
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C Basic Newton-Raphson loop - solution of the non-linear set
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C for the unknown vector P, consistiong of AH, ANH (neutral
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C hydrogen number density) and ANE.
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C
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10 IT=IT+1
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C
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C procedure STATE determines Q (and DQN) - the total charge (and its
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C derivative wrt temperature) due to ionization of all atoms which
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C are considered (both explicit and non-explicit), by solving the set
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C of Saha equations for the current values of T and ANE
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C
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CALL STATE(ID,T,ANE,Q)
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QH=QH0*2./PFSTD(1,1)
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C
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C Auxiliary parameters for evaluating the elements of matrix of
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C linearized equations.
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C Note that complexity of the matrix depends on whether the hydrogen
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C molecule is taken into account
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C Treatment of hydrogen ionization-dissociation is based on
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C Mihalas, in Methods in Comput. Phys. 7, p.10 (1967)
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C
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IF(IATREF.EQ.IATH) THEN
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G2=QH/ANE
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G3=0.
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G4=0.
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G5=0.
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D=0.
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E=0.
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G3=QM*ANE
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A=UN+G2+G3
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D=G2-G3
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IF(IT.LE.1) THEN
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IF(IH2.EQ.0) THEN
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F1=UN/A
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FE=D/A+Q
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ELSE
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E=G2*QP/Q2
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B=TWO*(UN+E)
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GG=ANE*Q2
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C1=B*(GG*B+A*D)-E*A*A
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C2=A*(TWO*E+B*Q)-D*B
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C3=-E-B*Q
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F1=(SQRT(C2*C2-4.*C1*C3)-C2)*HALF/C1
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FE=F1*D+E*(UN-A*F1)/B+Q
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END IF
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AH=ANE/FE
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ANH=AH*F1
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END IF
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AE=ANH/ANE
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GG=AE*QP
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E=ANH*Q2
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B=ANH*QM
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C
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C Matrix of the linearized system R, and the rhs vector S
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C
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R(1,1)=YTOT(ID)
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c R(1,2)=0.
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r(1,2)=-two*(anh*q2+gg)
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R(1,3)=UN
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R(2,1)=-Q
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R(2,2)=-D-TWO*GG
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R(2,3)=UN+B+AE*(G2+GG)-DQN*AH
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R(3,1)=-UN
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R(3,2)=A+4.*(anh*q2+GG)
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R(3,3)=B-AE*(G2+TWO*GG)
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S(1)=AN-ANE-YTOT(ID)*AH+anh*(anh*q2+gg)
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S(2)=ANH*(D+GG)+Q*AH-ANE
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S(3)=AH-ANH*(A+TWO*(anh*q2+GG))
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C
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C Solution of the linearized equations for the correction vector P
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C
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CALL LINEQS(R,S,P,3,3)
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C
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C New values of AH, ANH, and ANE
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C
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AH=AH+P(1)
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ANH=ANH+P(2)
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DELNE=P(3)
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ANE=ANE+DELNE
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C
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C hydrogen is not the reference atom
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C
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ELSE
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C
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C Matrix of the linearized system R, and the rhs vector S
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C
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IF(IT.EQ.1) THEN
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ANE=AN*HALF
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AH=ANE/YTOT(ID)
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END IF
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R(1,1)=YTOT(ID)
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R(1,2)=UN
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R(2,1)=-Q-QREF
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R(2,2)=UN-(DQN+DQNR)*AH
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S(1)=AN-ANE-YTOT(ID)*AH
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S(2)=(Q+QREF)*AH-ANE
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C
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C Solution of the linearized equations for the correction vector P
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C
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CALL LINEQS(R,S,P,2,3)
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AH=AH+P(1)
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DELNE=P(2)
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ANE=ANE+DELNE
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END IF
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C
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C Convergence criterion
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C
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IF(ANE.LE.0.) ANE=1.D-7*AN
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IF(ABS(DELNE/ANE).GT.1.D-6.AND.IT.LE.20) GO TO 10
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C
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C ANEREL is the exact ratio betwen electron density and total
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C particle density, which is going to be used in the subseguent
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C call of ELDENS
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C
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ANEREL=ANE/AN
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AHTOT=AH
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IF(IATREF.EQ.IATH) THEN
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c AHMOL=TWO*ANH*(ANH*Q2+ANH/ANE*QP)/AH
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AHMOL=ANH*ANH*Q2
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ANP=ANH/ANE*QH
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ANHMI=ANH*ANE*QM
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anhn=anh+anp+anhmi+2.*ahmol
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wmm(id)=wmy(id)/(ytot(id)-ahmol/anhn)*hmass
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END IF
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C
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RETURN
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END
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