Point-charge calculations

YBa2Cu30y, YBa2Cu30g EFG tensor, point charge calculation, charge states, hole on O positions... 

RBa2Cu307 ceramics (R is a rare-earth metal or yttrium) EFG tensor, comparison with point charge calculation, spatial distribution of electron defects in the lattice... 

Hutchings, M.T. (1964) Point-charge calculations of energy levels of magnetic ions in crystalline electric. Fields Solid State Phys., 16, 227-273. 

Starting from ionization radii, r o, and using experimentally measured values of dissociation energy and interatomic distance for homonuclear diatomic molecules, a self-consistent set of characteristic radii, suitable for the point-charge calculation of bonding parameters, of both homonuclear and... 

Before refining these values, and adding dipole-dipole repulsions and induced dipoles, the top H20 was examined to see if it would influence the most probable bottom position. Because DP multipole point-charge calculations are tedious, some simplifying assumptions were made. The H30+ lone pair points directly at the O in the top H20, whose lone pairs point downwards in either a symmetrical or Verwey position. However, the repulsions between the 6 H30+ bond electrons and the 4 top H20 lone pair electrons appear to steer the... 

Figure 5.3 Schematic diagram to demonstrate the electrostatic point-charge calculation of bond dissociation energy.

Empirical force field calculations (MM2(8S)) using atomic point charges calculated by AMI calculations (MM2 // AMI) correctly reproduce the AMI surface for heterocyclic betaines 55, 126, and 127 (93JST105). The methodology allows extensive conformational analysis of medium to large-size molecules by semiempirical calculations (AMI). The interaction energies for the dimerization of these betaines have also been well reproduced. 

Modern discussions of an electrostatic model of the H bond are more sophisticated than the earliest point charge calculations. Theorists believe that the charge distribution of the nonbonded electrons must be... 

Table 6. Point charge calculations with and without conduction electron screening effects in NdAl3 to obtain that will yield B = 1.766 K. Zjvjd is taken as + 3 and 03 = 0-5 (79).

If there are net charges present, as in proteins, the point charge approximation involves no extra calculation, but the dipole-dipole method requires that charge-charge and charge-dipole interactions also be carried out. The results are similar either way, but the point charge calculation can be carried out more quickly, and this method is usually used for large molecule calculations. 

In liquid solution at 25° C, the dissolved PaCBHit) is monomeric and of symmetry. Under these conditions there are five crystal field levels T7, r8, and r6, r7, r8 of the 2Fs/2 (ground) and 2F7/2 levels. Point charge calculations (20) give the Tq( F5/2) level as the ground state. 

Table 2. 10 Dq parameters of some 3d fluorides. Point charge calculations were carried out using Hartree-Fock (H.F.) or Staler functions...

Point-charge calculations of the crystal-field parameters for R CaW04 have been performed (Beiderbick et al., 1978 Brown et al., 1970) induced point dipole contributions to the crystal-field parameters have also been determined... 

Huang, C.Y., K. Sugawara and B.R. Cooper, 1976, EPR studies of exdted-state exchange and crystal-field effects in rare-earth compounds, in Int. Conf on Crystal-Field Effects in Metals and Alloys, ed. A. Furrer (Plenum Press, New York) pp. 5-60. Hutchings, M.T., 1964, Point charge calculations of energy levels of magnetic ions in crystalline electric fields, in Solid State Physics, Vol. 16, eds F. Seitz and D. Tumball (Academic Press, New York) pp. 227-273. 

An important application in that respect is distinguishing cis and trans configurations of an octahedral 64(011)2 (or (0H)402) Fe " coordination, which quite often occurs in mineralogical systems (Fig. 3.3). Simple point-charge calculations show that the quadrupole splitting should follow the relation Atrans = Ads-... 

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