• 제목/요약/키워드: Hydrogen Bond

검색결과 593건 처리시간 0.019초

Quantum Mechanical Study of van der Waals Complex. Ⅰ.The $H^2$ Dimer Using the DFT and the Multi-Coefficient G2/G3 Methods

  • 김창신;김상준;이용식;김용호
    • Bulletin of the Korean Chemical Society
    • /
    • 제21권5호
    • /
    • pp.510-514
    • /
    • 2000

  • Molecular hydrogen dimer, ($H_2)_2$ is a weakly bound van der Waals complex. The configuration of two hydrogen molecules and the potential well structure of the dimer have been the subjects of various studies among chemists and astrophysicists. In this study, we used DFT, MCG2, and MCG3 methods to determine the structure and energy of the molecular hydrogen dimer. We compared the results with previously reported ab initio method results. The ab initio results were also recalculated for comparison. All optimized geometries obtained from the MP2 and DFT methods are T-shaped. The H-H bond lengths for the dimer are almost the same as those of monomer. The center-to-center distance depeds on the levels of theory and the size of the basis sets. The bond lengths of the $H_2$ molecule from the MCG2 and MCG3 methods are shown to be in excellent agreement with the experimental value. The geometry of optimized dimer is T-shaped, and the well depths for the dimerization potential are very small, being 23 $cm-^1$ and 27 $cm-^1$ at the MCG2 and MCG3 levels, respectively. In general the MP2 level of theory predicts stronger van der Waals than the DFT, and agrees better with the MCG2 and MCG3 theories.

  • https://doi.org/10.5012/bkcs.2000.21.5.510 인용 PDF

Terahertz Spectral Characteristics of Electrolyte Solutions under Different Magnetic Fields

  • Shao, Siyu;Huang, Haiyun;Peng, Bo;Wang, Guoyang;Ye, Ping;Wang, Jiahui;Su, Bo;Cui, Hailin;Zhang, Cunlin
    • Current Optics and Photonics
    • /
    • 제6권3호
    • /
    • pp.337-343
    • /
    • 2022

  • Microfluidic chips are new devices that can manipulate liquids at the micrometer level, and terahertz (THz) time-domain spectroscopy has good applicability in biochemical detection. The combination of these two technologies can shorten the distance between sample and THz wave, reduce THz wave absorption by water, and more effectively analyze the kinetics of biochemical reactions in aqueous solutions. This study investigates the effects of different external magnetic field intensities on the THz transmission characteristics of deionized water, CuSO4, CuCl2, (CH3COO)2Cu, Na2SO4, NaCl, and CH3COONa; the THz spectral intensity of the sample solutions decrease with increasing intensity of the applied magnetic field. Analysis shows that the magnetic field leads to a change in the dipole moment of water molecules in water and electrolyte solutions, which enhances not only the hydrogen-bond networking ability of water but also the hydration around ions in electrolyte solutions, increasing the number of hydrogen bonds. Increasing the intensity of this magnetic field further promotes the hydrogen-bond association between water molecules, weakening the THz transmission intensity of the solution.

  • https://doi.org/10.3807/COPP.2022.6.3.337 인용 PDF KSCI

실리카 수산기의 산성에 관한 양자화학적 해석 (Quantum Chemical Calculations of Silica Hydroxyls as Acid Site)

  • 김명철
    • 공업화학
    • /
    • 제8권2호
    • /
    • pp.262-266
    • /
    • 1997

  • 실리카 표면 수산기를 나타내는 분자모델에 대해 CNDO/2계산을 수행하여 Wiberg결합차수, 전체에너지, LUMO에너지, 쌍극자모멘트 및 형식전하를 얻었다. 제안된 모델들의 Br${\ddot{o}}$nsted산성도는 Wiberg결합차수를 이용하여 서술하였다. 계산된 결합차수값들은 수소결합에 따라 큰 차이를 나타내었다. 그러나 실리카 표면수산기의 Lewis산성도는 수산기의 구조와 무관하였다.

  • PDF