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  • 1
    Electronic Resource
    Electronic Resource
    Calculation of nuclear magnetic shieldings. XIII. Gauge-origin independent relativistic effects (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 131-137 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The gauge-origin independent expression for the relativistic nuclear magnetic shieldings was derived from the Douglas-Kroll transformation of the no-pair equation and the use of the gauge including atomic orbitals (GIAOs) proposed by London. Using our expression the relativistic spin free effect on the nuclear magnetic shieldings was evaluated for the four hydrogen halide molecules, HF, HCl, HBr, and HI, at the coupled Hartree-Fock (CHF) level with uncontracted Cartesian Gaussian-type basis sets. It was found that the GIAO-CHF results are very similar to the shielding values calculated with the fixed gauge origins at the halogen nuclei. The calculated results showed that the spin independent relativistic effect produces high-field shifts at both the halogen nuclei and protons in the hydrogen halides. However, the computed spin free effect was too small to interpret the very large upshield proton shifts observed in HBr and HI molecules. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478089
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  • 2
    Electronic Resource
    Electronic Resource
    Calculation of nuclear magnetic shieldings. XII. Relativistic no-pair equation (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 3854-3862 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A Schrödinger-Pauli type two-component perturbation theory has been presented for the calculation of relativistic effects of nuclear magnetic shieldings. The expression for the relativistic nuclear magnetic shieldings are derived from the Douglas-Kroll transformation of the no-pair equation for a molecule, which bears a nuclear magnetic dipole moment, and which is placed in an external magnetic field. The exact form of the relativistic kinetic energy is included in the eigenvalue equation which is solved variationally. We calculated the relativistic mass correction effect on the nuclear magnetic shieldings in the four hydrogen halide molecules, HF, HCl, HBr, and HI, at the coupled Hartree-Fock (CHF) level. It was shown that the mass correction effect increases the nuclear magnetic shieldings of the halogen nuclei. The increments in the shieldings are proportional to about the third power of the atomic numbers of the halogen nuclei. This increase in the shieldings results from the mass correction effect concentrating the electrons in the vicinity of the heavy nucleus, the so-called relativistic contraction. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.475788
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  • 3
    Electronic Resource
    Electronic Resource
    Erratum: Calculation of nuclear magnetic shieldings. X. Relativistic effects [J. Chem. Phys. 105, 3175 (1996)] (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 2987-2987 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474125
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  • 4
    Electronic Resource
    Electronic Resource
    Calculation of nuclear spin–spin couplings. VIII. Vicinal proton–proton coupling constants in ethane (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 6597-6600 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Ab initio self-consistent-field (SCF) and electron correlation calculations have been carried out for the dihedral angle dependence of the vicinal proton–proton coupling constants, 3JHH, in ethane molecule. The four contributions to 3JHH, (JFC, JSD, JOP, and JOD) have been computed with the three different basis sets, [5s2p1d/2s1p], [5s3p1d/3s1p], and [7s4p2d/5s2p]. The Fermi contact (FC) contribution was largest and the spin–dipole (SD) contribution was smallest. The FC and orbital paramagnetic (OP) contributions showed large basis set dependence, but the SD and orbital diamagnetic (OD) contributions presented little basis set dependence. The calculated total SCF contribution to 3JHH was higher than the experimental coupling. Using the Møller–Plesset perturbation theory we have introduced electron correlation effects on the FC and OP terms. The correlation effects on the OP term was shown to be negligible. The second-order correlation in the FC term was very large and amounted to half of its SCF value in magnitude with opposite sign. However, the third-order correlation in the FC contribution was small. Unfortunately, the calculated 3JHH value including correlation corrections through third order was too small compared to the experimental one. The poor agreement between calculation and experiment is claimed to be due to higher than third-order correlations in the FC term. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.470388
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  • 5
    Electronic Resource
    Electronic Resource
    GeAs as a novel arsenic dimer source for n-type doping of Ge grown by molecular beam epitaxy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 3886-3889 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GeAs is successfully applied as a new arsenic dimer source for efficient n-type doping of Ge grown by molecular beam epitaxy. The arsenic fluxes emanating from GeAs Knudsen cells are not composed of arsenic tetramers, but only of arsenic dimers. High electron concentrations of up to 1.1×1020 cm−3 are achieved with GeAs, which is much larger than any ever obtained in antimony-doped Ge. The electron concentration in the arsenic-doped Ge films depends on the GeAs cell temperature with an activation energy of 2.5 eV, which coincides with that of the arsenic dimer beam flux generated from GeAs. Moreover, it is found that the electron and arsenic concentrations in the arsenic-doped Ge layer are identical. These results indicate that arsenic atoms are incorporated into Ge from the arsenic dimer beam, and that a very high electrical activation of the incorporated arsenic atoms is obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354483
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  • 6
    Electronic Resource
    Electronic Resource
    Calculation of nuclear spin–spin couplings. VII. Electron correlation effects on the five coupling mechanisms (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 2299-2304 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Electron correlation effects on the five mechanisms in the indirect nuclear spin–spin coupling tensors are computed for H 19F, H2 17O,14NH3,13CH4, H 35Cl, 33SH2, 31PH3, and 29SiH4. The five coupling mechanisms consist of Fermi-contact (FC), spin-dipole (SD), Fermi-contact and spin-dipole cross term (FC/SD), orbital paramagnetic (OP), and orbital diamagnetic (OD) terms. Electron correlation contributions through the second order are calculated by the finite-field many-body perturbation theory (FF-MBPT). The results show an extremely large contribution of the (FC/SD) cross term to the anisotropic part of the couplings. The FC contribution is dominant in the isotropic part, but the OP term is considerable in HF, HCl, and H2O. Electron correlation effects are large in the FC contribution. They are small, but not negligible, in the other terms except in the OD term.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463121
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  • 7
    Electronic Resource
    Electronic Resource
    Direct observation of hot-electron energy distribution in silicon metal–oxide–semiconductor field-effect transistors (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 1113-1115 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have directly observed the energy distributions of hot electrons in Si metal–oxide–semiconductor field-effect transistors. We used a lateral hot-electron transistor employing two potential barriers (an emitter barrier and a collector barrier) that divided the Si surface into three regions (the emitter, base, and collector). For an emitter-base voltage of −1.04 V, hot electrons with an excess energy of 0.7 eV were detected at the collector. The ratio of hot electrons to the injected electrons was 1.3%. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124613
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  • 8
    Electronic Resource
    Electronic Resource
    Single-electron memory using carrier traps in a silicon nitride layer (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 3555-3557 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A single-electron memory that utilizes carrier traps in a silicon nitride layer is proposed and experimentally demonstrated. The proposed device consists of an insulating three-layered memory node structure formed on a silicon substrate and a highly sensitive aluminum single-electron transistor that detects the written information. Successful memory operation is demonstrated with two types of write modes (slow/rapid) that depend on the state of the Si channel underneath. Carrier retention time is estimated to be around 45 min. Possibilities for both destructive and nondestructive readout are discussed. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124159
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  • 9
    Electronic Resource
    Electronic Resource
    Single-electron transistors fabricated from a doped-Si film in a silicon-on-insulator substrate (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 795-796 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We propose doped-thin-Si-film single-electron transistors (DS-SETs), which are fabricated from a highly doped Si film in a silicon-on-insulator substate by electron-beam lithography with a high-resolution resist (calixarene) and dry etching with CF4 gas. Because the structure can be well controlled, the DS-SET with a 45-nm-diam island shows nearly ideal characteristics of SETs with a charging energy of 1.4 meV. The results demonstrate that single-electron tunneling occurs through a single island without any isolated islands formed in potential fluctuations. We also discuss the discreteness of energy levels in a Si island. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120896
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  • 10
    Electronic Resource
    Electronic Resource
    Calculation of nuclear magnetic shieldings. XI. Vibrational motion effects (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 4692-4699 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Nuclear magnetic shieldings in first- and second-row hydrides were calculated with electron correlation taken into account through third order. The calculation was performed using London's gauge-invariant atomic orbitals (GIAOs) and finite-field Møller–Plesset perturbation theory (FF-MPPT). Furthermore, the vibrational motion corrections to the magnetic shieldings were evaluated. It was shown that the calculated isotropic shielding constants at the experimental geometries are higher than the experimental values, but that vibrational corrections are generally negative and improve the calculated shielding constants. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472310
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