It is shown that Symbolic Computation provides excellent tools for solving quantum mechanical problems by perturbation theory. The method presented herein solves for both the eigenfunctions and eigenenergies as power ...
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It is shown that Symbolic Computation provides excellent tools for solving quantum mechanical problems by perturbation theory. The method presented herein solves for both the eigenfunctions and eigenenergies as power series in the order parameter where each coefficient of the perturbation series is obtained in closed form. The algorithms are expressed in the Maple symbolic computation system but can be implemented on other systems. This approach avoids the use of an infinite basis set and some of the complications of degenerate perturbation theory. It is general and can, in principle, be applied to many separable systems.
We have calculated the pseudoscalar decay constants using the relativized quark model. We find fD≃240±20 MeV, fDs≃290±20 MeV, fB≃155±15 MeV, fBs≃210±20 MeV, and fBc≃410±40 MeV where the "...
We have calculated the pseudoscalar decay constants using the relativized quark model. We find fD≃240±20 MeV, fDs≃290±20 MeV, fB≃155±15 MeV, fBs≃210±20 MeV, and fBc≃410±40 MeV where the "errors" are our estimates of the reliability of the results. We used these values to study the Cabibbo-Kobayashi-Maskawa matrix elements. In particular, we combined our theoretical estimate of fB with the ARGUS/CLEO result for B0−B¯0 mixing to study the relation between |Vtd| and the t-quark mass. Recent measurements of |Vbc| and |Vbu| constrain mt≳70 GeV.
A three-dimensional lattice model for surfactant mixtures is presented in this paper. We extend the spin-1 or Blume-Emery-Griffiths model to include orientational degrees of freedom for each molecule. The model is the...
A three-dimensional lattice model for surfactant mixtures is presented in this paper. We extend the spin-1 or Blume-Emery-Griffiths model to include orientational degrees of freedom for each molecule. The model is then applied to ternary mixtures of surfactant with equal amounts of water and oil, and to binary mixtures of surfactant and water. For each case, phase diagrams are calculated using both mean-field and Bethe approximations. One interesting feature of this model is that it can exhibit long-period lamellar phases even though a simple Hamiltonian, containing only nearest-neighbor interactions, is used. The model also produces a ‘‘disorder line,’’ which is thought to divide the disordered phase of the ternary mixture into a region of ordinary disordered fluid and a region of microemulsion.
In this paper a review is given of recnet work in IR and Raman spectroscopy of the solid hydrogens. The main aim is to help the reader find literature references that are relevant to his or her interests.
In this paper a review is given of recnet work in IR and Raman spectroscopy of the solid hydrogens. The main aim is to help the reader find literature references that are relevant to his or her interests.
J. Yang, L. Lolle, J. Poll; Theory of the high frequency wind in interaction‐induced spectra, AIP Conference Proceedings, Volume 216, Issue 1, 1 December 1990,
J. Yang, L. Lolle, J. Poll; Theory of the high frequency wind in interaction‐induced spectra, AIP Conference Proceedings, Volume 216, Issue 1, 1 December 1990,
The long-term objective of this work is to produce a stable, efficient amorphous Si (a-Si) solar cell by a safe and inexpensive method. A process of reactive evaporation in a silane ambient was developed. This techniq...
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The long-term objective of this work is to produce a stable, efficient amorphous Si (a-Si) solar cell by a safe and inexpensive method. A process of reactive evaporation in a silane ambient was developed. This technique permits the fabrication of "intrinsic-like" a-Si:H. p-Type and n-type samples (carrier type was confirmed by Seebeck measurements) were prepared by the coevaporation of boron or reactive evaporation in a phosphorus ambient. The intrinsic-like samples have a room temperature conductivity of about 2 × 10−12 S cm−1, high temperature activation energies of 0.9 eV, and optical bandgaps near 1.8 eV. An all-amorphous Si:H pin diode was fabricated using this reactive evaporation process. The device consists of a tantalum contact, 20 – 40 nm of phosphorus doped a-Si:H, 300 – 400 nm of undoped a-Si:H, 20 – 40 nm of boron doped a-Si:H, and another tantalum contact.
It has been shown that it is possible to produce low-resistivity (10 2 ω cm) device-grade films of polycrystalline Zn 3 P 2 by the hot-wall technique and to produce low-leakage diodes (rectification ratio greater tha...
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It has been shown that it is possible to produce low-resistivity (10 2 ω cm) device-grade films of polycrystalline Zn 3 P 2 by the hot-wall technique and to produce low-leakage diodes (rectification ratio greater than 100) by evaporating magnesium or aluminium dots onto the resulting Zn 3 P 2 films. I–V and C–V measurements have been shown to be in qualitative agreement with the metal/ insulator/semiconductor model of Chattopadhyay and A.N. Daw, Solid State Electron., 29 (1986) 555.) which involves a patchy oxide between the metal and semiconductor regions. If the difference between the Fermi level and the valence band edge for our polycrystalline Zn 3 P 2 films is assumed to be the same as that found by Szatkowski and Sieranski for single-crystal Zn 3 P 2 (J. Szatkowski and K. Sieranski, Solid State Electron., 31 (1988) 257.) it is shown that it is possible to determine values of C 2 and δ p /δ, parameters entering the model of Chattopadhyay and Daw. The C–V results on the Mg/Zn 3 P 2 and Al/Zn 3 P 2 diodes can be interpreted as giving values for the carrier concentration N A in the Zn 3 P 2 that differ by a factor of 11, and some possible reasons for this are examined.
I review the status of the constituent quark model. I begin by showing that phenomenological heavy-quark potentials are in qualitative agreement with potentials calculated from first principles using the techniques of...
I review the status of the constituent quark model. I begin by showing that phenomenological heavy-quark potentials are in qualitative agreement with potentials calculated from first principles using the techniques of lattice QCD. I next argue that it is reasonable to extend the constituent quark model to light-quark systems where nonrelativistic approximations are no longer valid. We find that both mesons and baryons can be described in a «relativized» quark model which suggests a connection between the quark model and the fundamental theory, QCD. In the final section I review how the quark model is applied to multiquark systems. Using the example of six-quark systems it is seen that the qualitative features of nuclear physics can be derived from the quark model.
The magnetic penetration depth in the local limit λ(T) for a high-Tc superconductor has been calculated within the electron pairing induced by holes model proposed by us recently. The derivation of the formula for λ...
The magnetic penetration depth in the local limit λ(T) for a high-Tc superconductor has been calculated within the electron pairing induced by holes model proposed by us recently. The derivation of the formula for λ(T) is based on a new expression for the current-density operator which takes into account the nonparabolic band structure of the conduction electrons. Our numerical results for the temperature dependence of λ(T) when the hole concentration δ=0.263 (which corresponds to 90-K superconductors) are near to the BCS results for a conventional superconductor and also agree qualitatively with the experimental data on the single crystal of YBa2Cu3O7. Our value for the zero-temperature penetration depth is also close to the experimental values for the single crystals of the above material.
We present the classical and quantum versions of collision induced absorption spectra for three exactly solvable 1-D models, and obtain the asymptotic behaviour at high frequency. It is found that the quantum spectra ...
We present the classical and quantum versions of collision induced absorption spectra for three exactly solvable 1-D models, and obtain the asymptotic behaviour at high frequency. It is found that the quantum spectra fall off more slowly than the classical, and for realistic systems, they both fall off more slowly than exponential. An improved version of the Landau-Lifshitz WKB method is suggested as a numerically viable method for calculating the high frequency wing in quantum spectra and is tested on the exactly solvable models. The error is found to be negligible in two models and tolerable in the third model, even for the least classical system. Our discussion of an extension of the method using exact wavefunctions increases its scope beyond the collision induced absorption problem.
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