1492 Journal of Chemical Education • Vol. 77 No. 11 November 2000 • JChemEd.chem.wisc.edu The purpose of this article is to comment on the pedagogical ramifications of the recently claimed observation of d orbitals and the way in which these results were first announced and subsequently reported (1–6 ). Atomic orbitals—their use in writing electronic configurations and as a means of rationalizi...

We address the role played by orbital degeneracy in strongly correlated transition metal compounds. The mechanisms of magnetic and orbital interactions due to double exchange (DE) and superexchange (SE) are presented. Specifically, we study the effective spin-orbital models derived for the d ions as in KCuF3, and for the d ions as in LaMnO3, for spins S = 1/2 and S = 2, respectively. The magnet...

A novel contact-first approach for III–V FinFETs and trigate MOSFETs is presented. In this process, the metal contact is sputtered on the as-grown semiconductor heterostructure, and the contact metal is used as a part of the fin dryetch mask. We demonstrate this technique in Mo/n+-InGaAs contact structures with fin widths in the range of 50 to 300 nm. We have measured contact resistance in the ...

It is shown how previously reported bond energy equations (Van Hooydonk, 1973) can be re­ generated starting from the assumptions (i) that the valence-orbital energy of an element in a bond can be expressed as a function of its occupancy number (Iczkowski-Margrave, 1961) and (ii) that the potential around an atom in a bond vanishes as soon as its valence orbital is doubly occupied (Ferreira, 19...

We present the first gauge-origin independent formulation of Jones birefringence at the Hartree-Fock level of theory. Gauge-origin independence is achieved through the use of London atomic orbitals. The implementation is based on a recently proposed atomic orbital-based response theory formulation that allows for the use of both time- and perturbation-dependent basis sets [Thorvaldsen, Ruud, Kr...

The purpose of the present paper is to describe a method, in quantitative sense, of discussing the isolobal analogy of fragments (or molecules) proposed by Hoffmann. The »Frontier Hybrid Orbitals (FHO)« are used to represent the directional, fronti er orbitals of the central atom, which have the same meaning as the »lobes« involved in the concept of isolobal analogy. The calculatio n of Frontie...

We suggest a possible scenario for magnetic transition under pressure in dimerised systems where electrons are localised on molecular orbitals. The mechanism of transition is not related with competition between kinetic energy and on-site Coulomb repulsion as in Mott-Hubbard systems, or between crystal-field splitting and intra-atomic exchange as in classical atomic spin-state transitions. Inst...

An effort is accounted for in the present paper to exhibit the recently actively investigated connection between the search and use of ”orbitals” as basis sets in applied quantum mechanics and current advances in the mathematics of special functions and orthogonal polynomials, which are in turn motivated by the developments of the quantum theory of angular momentum. The latter theory in modern ...

Theoretical reasons for metallic behavior among diverse Zintl phases have generally not been pursued at an advanced level. Here, the electronic structure of Ca5Ge3 (Cr5B3 type), which can be formulated (Ca+2)5(Ge2-6)Ge-4 in oxidation states, has been explored comparatively by means of semiempirical and first-principles density functional methods. The FP-APW calculations show that alkaline-earth...

The structure and shape of the polypeptide chain of proteins are determined by the hybridized states of atomic orbitals in the molecular chain. The calculated s ratio in the sp hybrid orbitals is computed from the fractal dimension D of 81 proteins. The tertiary structures of 8 proteins covering 4 structural classes are analyzed. The proteins in the β-structural class are distinguished quantita...