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Electron density dictionary (rhoCIF) version 1.0.1

Category ATOM_RHO_MULTIPOLE

Name:
'_atom_rho_multipole_[rho]'

Definition:

   This category contains information about the multipole
   coefficients used to describe the electron density.
   High-resolution X-ray diffraction methods enable the
   determination of the electron density distribution in
   crystal lattices and molecules, which in turn allows for a
   characterization of chemical interactions (Coppens, 1997;
   Koritsanszky & Coppens, 2001). This is accomplished by
   the construction of a mathematical model of the charge
   density in a crystal and then by fitting the parameters of
   such a model to the experimental pattern of diffracted
   X-rays. The model on which this dictionary is based
   is the so-called multipole formalism proposed by Hansen
   & Coppens (1978). In this model, the electron density in
   a crystal is described by a sum of aspherical "pseudoatoms"
   where the pseudoatom density has the form defined in the
   _atom_rho_multipole_* items. Each pseudoatom density
   consists of terms representing the core density, the spherical
   part of the valence density and the deviation of the valence
   density from sphericity. The continuous electron density in the
   crystal is then modelled as a sum of atom-centred charge
   distributions. Once the experimental electron density has been
   established, the "atoms in molecules" theory of Bader (1990)
   provides tools for the interpretation of the density
   distribution in terms of its topological properties.


   Ref:  Bader, R. F. W. (1990). Atoms in molecules: a quantum
           theory. Oxford University Press.
         Coppens, P. (1997). X-ray charge densities and chemical
           bonding. Oxford University Press.
         Hansen, N. K. & Coppens, P.  (1978). Acta Cryst. A34,
           909-921.
         Koritsanszky, T. S. & Coppens, P. (2001). Chem. Rev. 101,
           1583-1621.

Example:

Example 1 - Multipole coefficients for the nickel ion in [Ni(H3L)][NO3][PF6], [H3L = N,N',N''-tris(2-hydroxy-3-methylbutyl)-1,4,7-triazacyclononane] [G.T. Smith et al. (1997). J. Am. Chem. Soc. 119, 5028-5034].
 
    loop_
    _atom_rho_multipole_atom_label
    _atom_rho_multipole_coeff_Pv
    _atom_rho_multipole_coeff_P00
    _atom_rho_multipole_coeff_P11
    _atom_rho_multipole_coeff_P1-1
    _atom_rho_multipole_coeff_P10
    _atom_rho_multipole_coeff_P20
    _atom_rho_multipole_coeff_P21
    _atom_rho_multipole_coeff_P2-1
    _atom_rho_multipole_coeff_P22
    _atom_rho_multipole_coeff_P2-2
    _atom_rho_multipole_coeff_P30
    _atom_rho_multipole_coeff_P31
    _atom_rho_multipole_coeff_P3-1
    _atom_rho_multipole_coeff_P32
    _atom_rho_multipole_coeff_P3-2
    _atom_rho_multipole_coeff_P33
    _atom_rho_multipole_coeff_P3-3
    _atom_rho_multipole_coeff_P40
    _atom_rho_multipole_coeff_P41
    _atom_rho_multipole_coeff_P4-1
    _atom_rho_multipole_coeff_P42
    _atom_rho_multipole_coeff_P4-2
    _atom_rho_multipole_coeff_P43
    _atom_rho_multipole_coeff_P4-3
    _atom_rho_multipole_coeff_P44
    _atom_rho_multipole_coeff_P4-4
    _atom_rho_multipole_kappa
    _atom_rho_multipole_kappa_prime0
    _atom_rho_multipole_kappa_prime1
    _atom_rho_multipole_kappa_prime2
    _atom_rho_multipole_kappa_prime3
    _atom_rho_multipole_kappa_prime4
    Ni2+(1)  2.38(4)  0.32(4)  0.00  0.00 -0.02(1)
             0.00(2)  0.00     0.00  0.00  0.00
            -0.08(1)  0.00     0.00  0.00  0.00      0.06(1)  -0.04(1)
             0.05(1)  0.00     0.00  0.00  0.00     -0.20(1)   0.08(1)
             0.00     0.00
             1.04(1)  0.44(1)  0.44  1.15(4)   0.44  1.15



Type: null

Category: category_overview