ADAS Subroutine c6chrg

      SUBROUTINE C6CHRG( SYMBD , IZD   , SYMBR , IZR   , IDZ0  ,
     &                   IRZ0  , IRZ1  , IRZ2  , NGRND , NBOT
     &                 )
C
C
C-----------------------------------------------------------------------
C
C  ****************** FORTRAN77 SUBROUTINE: C6CHRG *********************
C
C  PURPOSE:  SETS UP NUCLEAR CHARGE OF DONOR AND NULEAR, INITIAL AND
C            FINAL CHARGES OF RECEIVER. CHECKS VALIDITY OF RECEIVER
C            CHARGES. ALSO SETS GROUND STATE N LEVEL AND LOWEST N LEVEL
C            FOR TABULAR OUTPUTS.
C
C  CALLING PROGRAM: ADAS306
C
C  INPUT : (C*2)  SYMBD   = DONOR ELEMENT SYMBOL.
C  INPUT : (I*4)  IZD     = DONOR ION CHARGE.
C  INPUT : (C*2)  SYMBR   = RECEIVER ELEMENT SYMBOL.
C  INPUT : (I*4)  IZR     = RECEIVER ION CHARGE.
C
C  OUTPUT: (I*4)  IDZ0    = DONOR NUCLEAR CHARGE.
C  OUTPUT: (I*4)  IRZ0    = RECEIVER NUCLEAR CHARGE.
C  OUTPUT: (I*4)  IRZ1    = RECEIVER ION INITIAL CHARGE.
C  OUTPUT: (I*4)  IRZ2    = RECEIVER ION FINAL CHARGE.
C  OUTPUT: (I*4)  NGRND   = PRINCIPAL QUANTUM NUMBER OF GROUND STATE.
C  OUTPUT: (I*4)  NBOT    = MINIMUM PRINCIPAL QUANTUM NUMBER.
C
C ROUTINES:
C           ROUTINE     SOURCE      BRIEF DESCRIPTION
C           ------------------------------------------------------------
C           I4UNIT      ADAS        RETURNS UNIT NO. FOR OUTPUT MESSAGES
C           CXCHRG      ADAS        RETURNS DONOR NUCLEAR CHARGE AND
C                                   RECEIVER NULEAR, INITIAL AND FINAL
C                                   CHARGES.
C
C AUTHOR:  JONATHAN NASH (TESSELLA SUPPORT SERVICES PLC)
C          K1/0/81
C          JET EXT. 5183
C
C DATE:    11/11/93
C
C UNIX-IDL PORT:
C
C AUTHOR:  WILLIAM OSBORN (TESSELLA SUPPORT SERVICES PLC)
C
C DATE:    22ND MAY 1996
C
C VERSION: 1.1                          DATE: 22-05-96
C MODIFIED: WILLIAM OSBORN
C               - FIRST VERSION. NO CHANGES FROM IBM VERSION.
C
C-----------------------------------------------------------------------
C
C-----------------------------------------------------------------------
      CHARACTER*2         SYMBD,       SYMBR
      INTEGER             IDZ0,        IRZ0,        IRZ1,        IRZ2
      INTEGER             IZD,         IZR,         NBOT,        NGRND