Index

Core dictionary version 3.3.0

_exptl_crystal.F_000

Definition:

   
    The effective number of electrons in the crystal unit cell contributing
    to F(000). This 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 θ = 0°
     f~i~   = imaginary part of the scattering factors at θ = 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
    https://dictionary.iucr.org/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