k⋅ptheory of energy bands, wave functions, and optical selection rules in strained tetrahedral semiconductors

1995 ◽  
Vol 51 (23) ◽  
pp. 16695-16704 ◽  
Author(s):  
P. Enders ◽  
A. Bärwolff ◽  
M. Woerner ◽  
D. Suisky
Keyword(s):  
Wave Functions ◽  
Energy Bands ◽  
Selection Rules ◽  
Tetrahedral Semiconductors

An alternative mechanism for spin-forbidden photo-ionization of diatomic molecules and its rotation–electronic selection rules

1990 ◽  
Vol 68 (2) ◽  
pp. 177-183 ◽  
Author(s):  
Ying-Nan Chiu ◽  
Lue-Yung Chow Chiu
Keyword(s):  
Diatomic Molecules ◽  
Rotational Level ◽  
Electric Quadrupole ◽  
Chem Phys ◽  
Electric Dipole Transition ◽  
Wave Functions ◽  
Alternative Mechanism ◽  
Selection Rules ◽  
Photon Ionization ◽  
Photo Ionization

The spin-forbidden photo-ionization of diatomic molecules is proposed. Spin orbit interaction is invoked resulting in the correction and mixing of the wave functions of different multiplicities. The rotation–electronic selection rules given, but not proven, by Dixit and McKoy for Hund's case a based on the conventional mechanism of electric dipole transition (see Chem. Phys. Lett. 128, 49 (1986) are rederived and expressed in a different format. This new format permits the generalization of the selection rules to other photo-ionization transitions caused by the magnetic dipole, the electric quadrupole, and the two- and three-photon operators. These selection rules, which are for transitions from one specific rotational level of a given Kronig reflection symmetry to another, will help understand rotational branching and the dynamics of interaction in the excited state. They will also help in the selective preparation of well-defined rovibronic states in resonant-enhanced multi-photon ionization processes.

On the Dynamical Spin Susceptibility of Paramagnetic La2CuO4

1990 ◽  
Vol 193 ◽  
Author(s):  
H. Winter ◽  
Z. Szotek ◽  
W. M. Temmerman
Keyword(s):  
Local Density ◽  
Spin Susceptibility ◽  
The Body ◽  
Wave Functions ◽  
Matrix Elements ◽  
Electron Wave ◽  
Energy Bands ◽  
Fermi Surface Nesting ◽  
The Matrix ◽  
Dynamical Spin

ABSTRACTThe self-consistent one-electron wave functions and energy bands obtained by the LMTO-ASA method within the local density approximation (LDA) are used to calculate the wave vector and frequency dependent non-interacting spin susceptibility of paramagnetic La2CuO4 in the body-centred tetragonal (bct) structure. We show that the tendency towards the antiferromagnetic instability is strongly dependent on the effects of the matrix elements which lead to a substantial depression of the susceptibility, especially near the X-point. The Fermi surface nesting properties, although important for the susceptibility, are by far not sufficient for the instability and the interband transitions turn out to be of great significance. Our results indicate that the susceptibility is at least 3 times too small to drive this system through a transition to the antiferromagnetic state, and we discuss possible reasons for this failure.

A Model Dielectric Function for Semiconductors

1975 ◽  
Vol 53 (23) ◽  
pp. 2549-2554 ◽  
Author(s):  
R. D. Grimes ◽  
E. R. Cowley
Keyword(s):  
Dielectric Function ◽  
Energy Gap ◽  
Interpolation Formula ◽  
Electron System ◽  
Wave Functions ◽  
Three Dimensions ◽  
Energy Bands ◽  
One Dimensional ◽  
Energy Gaps ◽  
The Relationship

The microscopic dielectric function is calculated for a simple model of a semiconductor, originally proposed by Penn, in which the energy bands and wave functions are those of a one-dimensional, nearly free electron system, isotropically extended to three dimensions. The dielectric function is evaluated numerically so that all unnecessary approximations are avoided. The relationship between the static dielectric constant and the energy gap is found to be[Formula: see text]where S0 is about 0.6. The results for finite wave vectors, for a range of energy gaps, have been fitted to an interpolation formula to facilitate their use.

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