Nelson Maldonado Parada - Academia.edu (original) (raw)
Uploads
Papers by Nelson Maldonado Parada
Journal of Physics C: Solid State Physics, 1971
Some properties of the Wannier functions with minimal widths in the limit of a weak periodic pote... more Some properties of the Wannier functions with minimal widths in the limit of a weak periodic potential are studied. The form factor of the Wannier function and its width are shown to be obtainable from simple geometric constructions in the reciprocal space.
Physical Review B, 1970
We discuss the problem of what phases should be attributed to the Bloch functions in order to obt... more We discuss the problem of what phases should be attributed to the Bloch functions in order to obtain Wannier functions with minimal widths. An exact solution to this problem is foundby means of the k'p perturbation formalism. We also consider localized crystal functions of a more general kind. These functions are found to obey a Schrodinger equation in reciprocal space, and may have some important assets when compared to the Wannier functions.
Physical Review B, 1971
The electronic energy levels associated with vacancies in PbTe are obtained through the Green's-f... more The electronic energy levels associated with vacancies in PbTe are obtained through the Green's-function method of Koster and Slater, the unperturbed Bloch functions being obtained from a relativistic K' 7 augmented-plane-wave (APW) energy-band calculation. APW oneelectron energies were obtained at I' and the corresponding eigenfunctions were used to obtain matrix elements of the relativistic momentum operator~between states at 1. These energies and matrix elements were used in a K~~secular equation to obtain energies and wave functions at approximately 4300 points in the Brillouin zone. With 11 relativistic bands at I', excellent results were obtained. Localized Wannier functions were constructed by taking suitable linear combinations of the unperturbed Bloch functions and these Wannier functions provided the basis in which the energy levels in the presence of the perturbing impurity potential were found. We have solved the vacancy problem using Wannier functions from nine bands (five valence and four conduction) and 13 lattice sites. The results obtained from this calculation showed that Pb vacancies produce p-type PbTe, whereas Te vacancies produce n-type PbTe, and in both cases, carriers are present at all temperatures.
Solid State Communications, 1978
Physical Review Letters, 1969
We present new results that the states associated with Pb or Te vacancies in PbTe lie well up in ... more We present new results that the states associated with Pb or Te vacancies in PbTe lie well up in the conduction band and that no localized states appear in the valence-conduction band gap. Holes and electrons due to Pb or Te vacancies cannot freeze out even at O'K giving PbTe the character of a metal at very low temperatures.
International Journal of Quantum Chemistry, 2009
Journal of Physics C: Solid State Physics, 1971
Some properties of the Wannier functions with minimal widths in the limit of a weak periodic pote... more Some properties of the Wannier functions with minimal widths in the limit of a weak periodic potential are studied. The form factor of the Wannier function and its width are shown to be obtainable from simple geometric constructions in the reciprocal space.
Physical Review B, 1970
We discuss the problem of what phases should be attributed to the Bloch functions in order to obt... more We discuss the problem of what phases should be attributed to the Bloch functions in order to obtain Wannier functions with minimal widths. An exact solution to this problem is foundby means of the k'p perturbation formalism. We also consider localized crystal functions of a more general kind. These functions are found to obey a Schrodinger equation in reciprocal space, and may have some important assets when compared to the Wannier functions.
Physical Review B, 1971
The electronic energy levels associated with vacancies in PbTe are obtained through the Green's-f... more The electronic energy levels associated with vacancies in PbTe are obtained through the Green's-function method of Koster and Slater, the unperturbed Bloch functions being obtained from a relativistic K' 7 augmented-plane-wave (APW) energy-band calculation. APW oneelectron energies were obtained at I' and the corresponding eigenfunctions were used to obtain matrix elements of the relativistic momentum operator~between states at 1. These energies and matrix elements were used in a K~~secular equation to obtain energies and wave functions at approximately 4300 points in the Brillouin zone. With 11 relativistic bands at I', excellent results were obtained. Localized Wannier functions were constructed by taking suitable linear combinations of the unperturbed Bloch functions and these Wannier functions provided the basis in which the energy levels in the presence of the perturbing impurity potential were found. We have solved the vacancy problem using Wannier functions from nine bands (five valence and four conduction) and 13 lattice sites. The results obtained from this calculation showed that Pb vacancies produce p-type PbTe, whereas Te vacancies produce n-type PbTe, and in both cases, carriers are present at all temperatures.
Solid State Communications, 1978
Physical Review Letters, 1969
We present new results that the states associated with Pb or Te vacancies in PbTe lie well up in ... more We present new results that the states associated with Pb or Te vacancies in PbTe lie well up in the conduction band and that no localized states appear in the valence-conduction band gap. Holes and electrons due to Pb or Te vacancies cannot freeze out even at O'K giving PbTe the character of a metal at very low temperatures.
International Journal of Quantum Chemistry, 2009