anchor.diff:      wvnr = 2d0 * Pi / wavelength
   
       !refractive indices
  -    refr_shell = shell_refr
  -    refr_core = core_refr
  +    refr_shell = cmplx( real(shell_refr), -1.*imag(shell_refr) )
  +    refr_core  = cmplx( real(core_refr ), -1.*imag(core_refr ) )
   
       !shell/core radius [um]
       rshell = radius_shell
       rcore  = radius_core
  -
   
       !get Mie coefficients for a sulfate coated BC particle with core 
       !radius r_core and shell radius rshell
  
positive.code:          PASS1  = .False.
  
        END IF
  
        XSHELL = RSHELL*WVNO
        XCORE  = RCORE*WVNO
  
negative.code:         radius_core,     &  ! core radius [um]
          wavelength          ! radiation wavelngth 
       
       complex (kind=ckind), intent(in) :: & 
          shell_refr,      &  ! shell refractive index
          core_refr           ! core  refractive index 
  
  