Index

Core dictionary version 3.0.14

_exptl_crystal.F_000

Definition:

   
     Number of electrons in the crystal unit cell contributing to F(000).
     It may contain dispersion contributions, and is calculated as
 
      F(000) = [ (sum f~r~)^2^ + (sum f~i~)^2^ ]^1/2^
 
      f~r~   = real part of the scattering factors at theta = 0
      f~i~   = imaginary part of the scattering factors at theta = 0
 
              the sum is taken over each atom in the unit cell
 
     For X-rays, non-dispersive F(000) is a positive number and counts
     the effective number of electrons in the unit cell; for neutrons,
     non-dispersive F(000) (which may be negative) counts the total
     nuclear scattering power in the unit cell. See
    http://reference.iucr.org/dictionary/F(000)

Type: Real

Definition method:

         If (_diffrn_radiation.probe == "neutron")  _units.code =  "femtometres"
    Else If (_diffrn_radiation.probe == "electron") _units.code =  "volts"
    Else                                            _units.code =  "electrons"

Category:
exptl_crystal