PROGRAM MAIN
      IMPLICIT DOUBLE PRECISION (A-H,O-Z)
      COMMON /SYMTAB/ SYMBAT(0:92)
      CHARACTER*2 SYMBAT
      DATA SYMBAT/    'XX','H ','He','Li','Be','B ','C ','N ','O '
     -     ,'F ','Ne','Na','Mg','Al','Si','P ','S ','Cl','Ar','K '
     -     ,'Ca','Sc','Ti','V ','Cr','Mn','Fe','Co','Ni','Cu','Zn'
     -     ,'Ga','Ge','As','Se','Br','Kr','Rb','Sr','Y ','Zr','Nb'
     -     ,'Mo','Tc','Ru','Rh','Pd','Ag','Cd','In','Sn','Sb','Te'
     -     ,'I ','Xe','Cs','Ba','La','Ce','Pr','Nd','Pm','Sm','Ee'
     -     ,'Gd','Tb','Dy','Ho','Er','Tm','Y ','Lu','Hf','Ta','W '
     -     ,'Re','Os','Ir','Pt','Au','Hg','Tl','Pb','Bi','Po','At'
     -     ,'Rn','Fr','Ra','Ac','Th','Pa','U '/

C optical Bohr spectra

      WRITE(6,*) ' we calculate the series n -> n+m ' 
      WRITE(6,*) ' for elements No Z '
      WRITE(6,*) ' the Rydberg constant is set to 109700 cm-1'
      WRITE(6,*) 
 100  CONTINUE
      WRITE(6,*)  ' give Z (Z=0 stops the program) '
      READ(5,*) NZ
      IF (NZ.GT.92) THEN
       WRITE(6,*) ' we are limited to Uranium (Z=92)'
       GO TO 100
      END IF
      IF (NZ.EQ.0) THEN
       WRITE(6,*) ' OK, we stop here '
       STOP
      END IF
      WRITE(6,*)  ' give N'
      READ(5,*) N1

      WRITE(6,*)
      WRITE(6,9000) SYMBAT(NZ),NZ-1,N1
 9000 FORMAT(' SERIES FOR ELEMENT : ',A2,I4,'+ and N = ',I4)
      WRITE(6,*)
      CALL CALCTR(NZ,N1)
      GO TO 100
C
      END 

      SUBROUTINE CALCTR(NZ,N1)
      IMPLICIT DOUBLE PRECISION (A-H,O-Z)

      N2=N1+1
      XLAMBD1=BOHR(NZ,N1,N2)
      N2=130000
      XLAMBD2=BOHR(NZ,N1,N2)
      write(6,9000) n1,xlambd1,xlambd2
 9000 FORMAT(' series starting from n = ',I3
     -     ,/,' longest lambda :  ',F12.2,' Angstroms '
     -     ,/,' limit of series : ',F12.2,' Angstroms ')
      DO N2=N1+1,N1+30
       XLAMB=BOHR(NZ,N1,N2)
       WRITE(6,9001) N1,N2,XLAMB
      END DO

      DO N2=N1+50,N1+500,50
       XLAMB=BOHR(NZ,N1,N2)
       WRITE(6,9001) N1,N2,XLAMB
      END DO

 9001  FORMAT(' TRANSITION ',I4,' -> ',I4,' : LAMBDA = ',F10.2
     $      ,' ANGSTROM') 
      RETURN
      END

      FUNCTION BOHR(NZ,N1,N2)
      IMPLICIT DOUBLE PRECISION (A-H,O-Z)

      R=109700.D0
      BOHR=DBLE(NZ*NZ)*(1.D0/(DBLE(N1*N1))-1.D0/DBLE(N2*N2))*R
      BOHR=1.D8/ABS(BOHR)

      RETURN
      END