Showing papers by "University of Crete published in 1981"
TL;DR: In this paper, the authors used the coherent potential approximation to calculate the electronic densities of states for a model of hydrogenated amorphous silicon, and demonstrated the restoration and widening of the band gap with increasing hydrogen content.
Abstract: We have used the coherent potential approximation to calculate the electronic densities of states for a model of hydrogenated amorphous silicon. The results demonstrate the restoration and widening of the band gap with increasing hydrogen content. In the valence band, excellent agreement with photoemission experiments is obtained. In the conduction band Si-H antibonding states are predicted that can be inferred from photoconductivity measurements.
91 citations
TL;DR: The Clifford algebras H (quaternions), N1 (dihedral Clifford algebra which is related to real 2-spinors), and S1 (algebra of Pauli matrices which are related to complex 2-spiders) were constructed in this article.
Abstract: A general construction of alternative algebras with three anticommuting elements and a unit is given. As an exhaustive result over the real and complex fields, we obtain the Clifford algebras H (quaternions), N1 (dihedral Clifford algebra which is related to real 2‐spinors), and S1 (algebra of Pauli matrices which is related to complex 2‐spinors). What is important is that the algebras N1 and S1 possess inverses everywhere except on a region akin to the light cone of the Minkowski space, while the quaternion algebra H has inverses everywhere except at the zero element. We discuss the reasons why the three algebras N1, H, and S1 are so difficult to distinguish in the representation space of 2×2 complex matrices.
34 citations
TL;DR: In this paper, the Cauchy-Riemann equations of holomorphy are extended to fields in higher dimensional spaces in a framework of Clifford algebras.
Abstract: The Cauchy–Riemann equations of holomorphy are extended to fields in higher‐dimensional spaces in a framework of Clifford algebras. The equations of holomorphy in Minkowski spacetime turn out to be the Maxwell equations in vacuum. The Lorentz gauge condition is a result of the holomorphy. Sources can be included in an extension of the residue theorem, where charges correspond to the residues.
23 citations
TL;DR: The Clifford algebra as mentioned in this paper is an abelian ring of dimension two with properties analogous to the complex field C. The ring has a string of singular inverses, and may be regarded as a singular field.
Abstract: The Clifford algebra Ω generated by the elements {1,ω} with (ω)2 = +1, is an abelian ring of dimension two with properties analogous to the complex field C. The ring Ω has a string of singular inverses, and may be regarded as a ’’singular field’’ which circumvents both the fundamental theorem of algebra and the Frobenius theorem. We construct two associative algebras of dimension four over Ω: the Clifford algebra Ω1 and the biquaternions of Clifford Ω2, and demonstrate that both algebras possess inverses everywhere except on a singular region akin to the light cone of the Minkowski space. Matrix representations are discussed, as well as the importance of the algebras Ω1 and Ω2, in the description of physical vector fields.
19 citations
TL;DR: In this paper, a space and SU(N) Lie algebra symmetrization of the states, stabilizes the Savvidy vaccum, but the constant chromoelectric field vacuum continues to be unstable after the symmetry.
17 citations
TL;DR: In this article, the Gaspari-Gyorffy theory for calculating the electron-phonon interaction was extended to incorporate a correction to the rigid-muffin-tin approximation (RMTA).
Abstract: The Gaspari-Gyorffy theory for calculating the electron-phonon interaction $\ensuremath{\lambda}$ is extended to incorporate a correction to the rigid-muffin-tin approximation (RMTA). This correction is achieved by constructing a potential which has the correct asymptotic behavior at large distances and reduces to essentially a uniform potential well inside the muffin-tin sphere. This method is particularly applicable to the simple metals where the usual RMTA underestimates $\ensuremath{\lambda}$. The results obtained without any adjustable parameter are in better agreement with the experimental data than those obtained by the RMTA.
10 citations
TL;DR: Theorem 3.3.3 as mentioned in this paper shows that a simple linear algebraic Chevalley group of universal type over K, the algebraic closure of the prime field F, p > 1.
8 citations
TL;DR: The range of applicability of the transport equation for photoelectrons in the ionosphere was extended to thermal energies as discussed by the authors, which enables one to calculate the photoelectron distribution in the important low energy region (i.e.
7 citations
TL;DR: It is proved that no asymptotic union nonbasis B of order h fulfills the following criterion of maximality: for every A belonging to F but not to B, B @?{A}; is an asymPTotic union basis ofOrder h.
4 citations
TL;DR: The uniform motion of a dislocation with a diatomic chain is little affected by Δ m (for small Δ m ) at high velocities υ (but υ / c 1 1 ).
4 citations
TL;DR: In this paper, it was shown that a critical energy exists in the symmetrized constant chromomagnetic field vacuum and that the second-order approximation to the q-q scattering amplitude vanishes at lower energies.
TL;DR: In this article, a mean-square-field approximation was introduced in the SU(2) gauge theory quantized in the temporal gauge by Goldstone and Jackiw, and the propagator of the spin-zero component of the gauge field was determined explicitly.
Abstract: A mean-square-field approximation is introduced in the SU(2) gauge theory quantized in the temporal gauge by Goldstone and Jackiw. The propagator of the (nonrelativistic) spin-zero component of the gauge field is determined explicitly. It is shown that the string equations can be derived by employing this particular mean-square-field approximation.