Atomic orbitals electron density

Drexel undergraduate students in both the lecture and the laboratory of physical chemistry have b n using TKISolver for such calculations as least squares fitting of experimental data, van der Waals gas calculations, and quantum mechanical computations (plotting particle-in-a-box wavefunctions, atomic orbital electron densities, etc.). I use TKISolver in lectures (on a Macintosh with video output to a 25" monitor) to solve simple equations and plot functions of chemical interest. 

The N-nuclear quadrupole resonance frequencies of pyridine and 4-picoline have been discussed in terms of the atomic orbital electron densities of the nitrogen atom. ... 

Unsaturated organic molecules, such as ethylene, can be chemisorbed on transition metal surfaces in two ways, namely in -coordination or di-o coordination. As shown in Fig. 2.24, the n type of bonding of ethylene involves donation of electron density from the doubly occupied n orbital (which is o-symmetric with respect to the normal to the surface) to the metal ds-hybrid orbitals. Electron density is also backdonated from the px and dM metal orbitals into the lowest unoccupied molecular orbital (LUMO) of the ethylene molecule, which is the empty asymmetric 71 orbital. The corresponding overall interaction is relatively weak, thus the sp2 hybridization of the carbon atoms involved in the ethylene double bond is retained. 

Schreckenbach, G., Ziegler, T., 1997b, Calculation of the g-Tensor of Electron Paramagnetic Resonance Spectroscopy Using Gauge-Including Atomic Orbitals and Density Functional Theory , J. Phys. Chem. A, 101, 3388. 

With an interaction as in Figure 42, the two 5a (Te-Te) orbitals that include the formally positively charged tricoordinate Te atoms accept electron density from the occupied 5p2 lone pair orbitals of the two central Te atoms. In this way the central Te-Te bond is shortened to about 264 pm through the two... 

Figure 2. Direct dependence of the one atom paramagnetic screening constant, on the orbital electron density, q, for carbon-13. Modified from Pugmire et aL (1968).

Holladay A, Leung PC, Coppens P (1983) Generalized relations between d-orbital occupancies of transition-metal atoms and electron-density multipole population parameters from X-ray diffraction data. Acta Crystallogr A 39 377-387... 

Figure 1.2 Electron density, 9a, for b and 2p atomic orbitals. The density of shading is roughly proportional to 92.

When the catalyst is illuminated, the ZnO bonds are excited and loosened. In the linear combination of the ZnO bonds (Eq. 25) the nonbonding form increases at the expense of the bonding forms. This means that there is a shift of the bond electrons from the oxygen to the zinc atom. The electron density in the orbitals of the Zn atoms is increased, while the electron density in the orbitals of the oxygen atoms is decreased as compared with that of the ground state of the bond. A similar state is generated by the oxygen desorption of the surface where electron-enriched zinc atoms remain. ZnO, as an n-conductor, even in the... 

The solvatochromism of H-complexes of 5-amino-l-methyl-4-nitropyrazole in aprotic protophilic media has been described by Kamlet-Taft empirical parameters. Specific solvation affects only one of the two long-wave bands, namely that corresponding to an electronic transition involving orbital electron density transfer from the H-bound nitrogen atom [1123],... 

To improve upon a double- basis, one generally adds polarization functions whose / values correspond to orbitals unoccupied in the free atoms. For example, to expand upon a double- basis for HjO, one would add 2p functions on H and 3d functions on O. Such functions are called polarization functions since they describe the polarization of atomic electron density arising from molecule formation. For example, if a H atom is placed in the electrostatic field of an O atom, its electron density will be polarized along the 0-H bond direction, a change that can be described by the mixing of H 2p character into the His wave function. 

R groups increase the stability of an alkene because R groups are sp hybridized, whereas the carbon atoms of the double bond are sp hybridized. Recall from Sections 1.1 OB and 2.5D that the percent -character of a hybrid orbital increases from 25% to 33% in going from sp to sp. The higher the percent s-character, the more readily an atom accepts electron density. Thus, sp hybridized carbon atoms are more able to accept electron density and hybridized carbon atoms are more able to donate electron density. 

The overlap of p orbitals on three or more adjacent atoms allows electron density to delocalize, thus adding stability (16.1). 

Figure 5-20 Plots of the electron density distributions associated with s orbitals. For any s orbital, this plot is the same in any direction (spherically symmetrical). The sketch below each plot shows a cross-section, in the plane of the atomic nucleus, of the electron cloud associated with that orbital. Electron density is proportional to r ip. ...

The main descriptors based on molecular orbital electron densities of the oth atom are the following. 

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