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Mel Levy - One of the best experts on this subject based on the ideXlab platform.

  • Density-functional exchange correlation through Coordinate scaling in adiabatic connection and correlation hole
    Physical review. A Atomic molecular and optical physics, 1991
    Co-Authors: Mel Levy
    Abstract:

    The exact exchange-correlation functional ${\mathit{E}}_{\mathrm{xc}}$[n] must be approximated in density-functional theory for the computation of electronic properties. By the coupling-constant integration (adiabatic-connection) formula we know that ${\mathit{E}}_{\mathrm{xc}}$[n]=${\mathcal{F}}_{0}^{1}$(${\mathit{V}}_{\mathit{e}\mathit{e}}^{\mathrm{\ensuremath{\alpha}}}$[n]-U[n])d\ensuremath{\alpha}, where ${\mathit{V}}_{\mathit{e}\mathit{e}}^{\mathrm{\ensuremath{\alpha}}}$[n] is the electron-electron repulsion energy of ${\mathrm{\ensuremath{\Psi}}}_{\mathit{n}}^{\mathrm{m}\mathrm{i}\mathrm{n},\mathrm{\ensuremath{\alpha}}}$, which is that wave function that yields the density n and minimizes 〈T^+\ensuremath{\alpha}V${\mathrm{^}}_{\mathit{e}\mathit{e}}$〉. Here \ensuremath{\alpha} is the coupling constant. Consequently, knowledge of the behavior of ${\mathit{V}}_{\mathit{e}\mathit{e}}^{\mathrm{\ensuremath{\alpha}}}$[n] as a function of \ensuremath{\alpha} ensures knowledge of ${\mathit{E}}_{\mathrm{xc}}$[n]. With this in mind and for the purpose of approximating ${\mathit{E}}_{\mathrm{xc}}$, it was previously established that (\ensuremath{\partial}${\mathit{V}}_{\mathit{e}\mathit{e}}^{\mathrm{\ensuremath{\alpha}}}$/\ensuremath{\partial}\ensuremath{\alpha})\ensuremath{\le}0. The present paper reveals that ${\mathit{V}}_{\mathit{e}\mathit{e}}^{\mathrm{\ensuremath{\alpha}}}$[n]=\ensuremath{\alpha}${\mathit{V}}_{\mathit{e}\mathit{e}}^{1}$[${\mathit{n}}_{1/\mathrm{\ensuremath{\alpha}}}$], where ${\mathit{n}}_{\mathrm{\ensuremath{\beta}}}$(x,y,z)=${\mathrm{\ensuremath{\beta}}}^{3}$n(\ensuremath{\beta}x,\ensuremath{\beta}y,\ensuremath{\beta}z), and where \ensuremath{\beta} is a Coordinate Scale factor.

Iu L - One of the best experts on this subject based on the ideXlab platform.

Samuel Krimm - One of the best experts on this subject based on the ideXlab platform.

  • Ab initio studies of the conformation dependence of the spectra of stable conformers of n-pentane and n-hexane
    The Journal of Physical Chemistry, 1993
    Co-Authors: Noemi G. Mirkin, Samuel Krimm
    Abstract:

    Scaled ab initio force fields were used to calculate normal-mode frequencies of the 14 stable conformers of n-pentane and n-hexane. Force constants were obtained from the 6-31G basis set because it did not exhibit the predictive problems of several others that were examined. Twelve local symmetry Coordinate Scale factors were optimized by fitting calculated modes to the well-assigned bands of trans-n-pentane. The rms deviation for 61 observed bands below 1500 cm -1 of all trans-n-pentane and n-hexane is 4.8 cm -1 . Assignments of some of these bands differ from those derived from empirical force fields

Song Hai - One of the best experts on this subject based on the ideXlab platform.

Noemi G. Mirkin - One of the best experts on this subject based on the ideXlab platform.

  • Ab initio studies of the conformation dependence of the spectra of stable conformers of n-pentane and n-hexane
    The Journal of Physical Chemistry, 1993
    Co-Authors: Noemi G. Mirkin, Samuel Krimm
    Abstract:

    Scaled ab initio force fields were used to calculate normal-mode frequencies of the 14 stable conformers of n-pentane and n-hexane. Force constants were obtained from the 6-31G basis set because it did not exhibit the predictive problems of several others that were examined. Twelve local symmetry Coordinate Scale factors were optimized by fitting calculated modes to the well-assigned bands of trans-n-pentane. The rms deviation for 61 observed bands below 1500 cm -1 of all trans-n-pentane and n-hexane is 4.8 cm -1 . Assignments of some of these bands differ from those derived from empirical force fields