scholarly journals Improved method for generating exchange-correlation potentials from electronic wave functions

2017 ◽  
Vol 146 (8) ◽  
pp. 084103 ◽  
Author(s):  
Egor Ospadov ◽  
Ilya G. Ryabinkin ◽  
Viktor N. Staroverov
Keyword(s):  
Wave Functions ◽  
Improved Method ◽  
Electronic Wave ◽  
Exchange Correlation ◽  
Electronic Wave Functions

Basis-Set Expansions of Relativistic Electronic Wave Functions

2007 ◽  
Author(s):  
Kenneth G. Dyall ◽  
Knut Faegri
Keyword(s):  
Relativistic Quantum ◽  
Finite Basis ◽  
Wave Functions ◽  
Basis Set ◽  
Electronic Wave ◽  
Nonrelativistic Case ◽  
Hartree Fock ◽  
Electronic Wave Functions ◽  
Basis Set Expansion ◽  
Molecular Calculations

There have been several successful applications of the Dirac–Hartree–Fock (DHF) equations to the calculation of numerical electronic wave functions for diatomic molecules (Laaksonen and Grant 1984a, 1984b, Sundholm 1988, 1994, Kullie et al. 1999). However, the use of numerical techniques in relativistic molecular calculations encounters the same difficulties as in the nonrelativistic case, and to proceed to general applications beyond simple diatomic and linear molecules it is necessary to resort to an analytic approximation using a basis set expansion of the wave function. The techniques for such calculations may to a large extent be based on the methods developed for nonrelativistic calculations, but it turns out that the transfer of these methods to the relativistic case requires special considerations. These considerations, as well as the development of the finite basis versions of both the Dirac and DHF equations, form the subject of the present chapter. In particular, in the early days of relativistic quantum chemistry, attempts to solve the DHF equations in a basis set expansion sometimes led to unexpected results. One of the problems was that some calculations did not tend to the correct nonrelativistic limit. Subsequent investigations revealed that this was caused by inconsistencies in the choice of basis set for the small-component space, and some basic principles of basisset selection for relativistic calculations were established. The variational stability of the DHF equations in a finite basis has also been a subject of debate. As we show in this chapter, it is possible to establish lower variational bounds, thus ensuring that the iterative solution of the DHF equations does not collapse. There are two basically different strategies that may be followed when developing a finite basis formulation for relativistic molecular calculations. One possibility is to expand the large and small components of the 4-spinor in a basis of 2-spinors. The alternative is to expand each of the scalar components of the 4-spinor in a scalar basis. Both approaches have their advantages and disadvantages, though the latter approach is obviously the easier one for adapting nonrelativistic methods, which work in real scalar arithmetic.

Analytic Raman intensities from molecular electronic wave functions

1986 ◽  
Vol 84 (1) ◽  
pp. 531-532 ◽  
Author(s):  
Michael J. Frisch ◽  
Yukio Yamaguchi ◽  
Jeffrey F. Gaw ◽  
Henry F. Schaefer ◽  
J. Stephen Binkley
Keyword(s):  
Wave Functions ◽  
Molecular Electronic ◽  
Electronic Wave ◽  
Electronic Wave Functions ◽  
Raman Intensities

Manifestation of the DX Centre in Heavily δ-Doped GaAs(Si)

1992 ◽  
Vol 281 ◽  
Author(s):  
S. Arscott ◽  
M. Missous ◽  
L. Dobaczewski ◽  
P. C. Harness ◽  
D. K. Maude ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Transport Properties ◽  
Electron Concentration ◽  
Low Temperatures ◽  
Molecular Beam ◽  
Wave Functions ◽  
Potential Well ◽  
Electronic Wave ◽  
Hall Measurements ◽  
Electronic Wave Functions

ABSTRACTShubnikov-de Haas and Hall measurements have been performed on singly delta doped GaAs(Si) structures, grown by molecular beam epitaxy, enabling us to study the effects of illumination and temperature upon bulk and individual subband, mobilities and carrier concentrations. In a highly doped sample, where the peak 3D electron concentration approaches 2×1019cm−3, we have observed novel changes in subband transport characteristics, not observed in the lower doped samples, which we attribute to the presence of DX centre phenomena. This paper explains the variations in individual subband transport properties due to a possible shift of the electronic wave functions contained in the potential well. This shift occurs due to a recombination-autoionization(R-A) process involving filled DX centres and free holes upon sample illumination at low temperatures.

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