• Title/Summary/Keyword: electronic bulletin

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Ab Initio Molecular Dynamics with Born-Oppenheimer and Extended Lagrangian Methods Using Atom Centered Basis Functions

  • Schlegel, H. Bernhard
    • Bulletin of the Korean Chemical Society
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    • v.24 no.6
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    • pp.837-842
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    • 2003
  • In ab initio molecular dynamics, whenever information about the potential energy surface is needed for integrating the equations of motion, it is computed “on the fly” using electronic structure calculations. For Born-Oppenheimer methods, the electronic structure calculations are converged, whereas in the extended Lagrangian approach the electronic structure is propagated along with the nuclei. Some recent advances for both approaches are discussed.

Structural and Electronic Properties of an Alkali Fulleride, $Rb_1C_{60}$

  • Lee, Hye Yeong;Jeong, Dong Un
    • Bulletin of the Korean Chemical Society
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    • v.17 no.1
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    • pp.43-45
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    • 1996
  • Structural and electronic properties of an alkali metal fulleride, Rb1C60, was studied. In spite of the chain structure with shortdistance between balls along the crystallographic a-direction, the electronic structure calculation study with the X-ray defined crystal structure shows that Rb1C60 is a three-dimensional metal at room temperature. This result is different from the magnetic experiments in which the compound was found to behave as a quasi-one-dimensional metal. Partial Fermi surface nesting is supposed to be the reason for the metal-insulator transition found in Rb1C60 at ∼50 K.

Collision-Induced Electronic Relaxation of Thiophosgene (S₁)

  • 김택수;Choi, Young S.
    • Bulletin of the Korean Chemical Society
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    • v.17 no.8
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    • pp.745-749
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    • 1996
  • Fluorescence from the electronically excited thiophosgene (Cl2CS) in its first excited singlet state (S1) is efficiently quenched by collision. Rates of the collision-induced electronic relaxation were obtained for various vibrational levels in the S1 state by measuring the fluorescence lifetimes. We found that the relaxation process is strongly energy-dependent; the rate consistently increases by a factor of ~40 with the increase of vibrational energy from 0 to 1450 cm-1. Collision-induced intersystem crossing from the S1 to the first triplet state (T1) is attributed to the major process responsible for the electronic relaxation.

Band Electronic Structure Study of Compound $(ET)_2ICl_2$ in Two Structural Modifications

  • Kang Dae Bok
    • Bulletin of the Korean Chemical Society
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    • v.15 no.6
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    • pp.428-432
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    • 1994
  • The crystals of ${\beta}-and\;{\beta}'-(ET)_2ICl_2$ have a modified structure of organic superconductor ${\beta}(ET)_2I_3$. These salts possess strictly different physical properties : the ${\beta}$ phase is a metal but the ${\beta}'$ phase is a semiconductor. Our band electronic structure calculations show that the ${\beta}$ phase is somewhat anisotropic 2D metal and the ${\beta}'$ phase with the 1D character in electronic structure is magnetic insulating, in good agreement with experimental indications.

Band Electronic Structure Study of Two-Dimensional Organic Metal (BEDT-TTF)2Cu5I6 with a Polymer Anion Layer

  • Dae Bok Kang
    • Bulletin of the Korean Chemical Society
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    • v.12 no.5
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    • pp.515-517
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    • 1991
  • The electronic behavior of a organic metal $(BEDT-TTE)_2$${Cu_5}{I_6}$ observed to be stable at low temperatures was examined by performing tight-binding band electronic structure calculations. The suppression of a metal-insulator tansition is likely to originate from its quasi-two-dimensional Fermi surface with no nesting, in agreement with experiment.