Browsing by Author Nguyen, Cong Toan

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  • 4076-97-8103-1-10-20171016.pdf.jpg
  • Article


  • Authors: Nguyen, Van Hung; Nguyen, Bao Trung; Nguyen, Cong Toan; Ha, Dang Khoa (2017)

  • Debye-Waller factors (DWFs) of metallic Cu (fcc crystal) in X-ray absorption fine structure (XAFS) presented in terms of cumulant expansion have been studied using the anharmonic correlated Debye model (ACDM). This ACDM is derived using the many-body perturbation approach and the anharmonic effective potential that includes the first shell near neighbor contributions to the vibration between absorber and backscatterer atoms. Analytical expressions of three first XAFS cumulants of Cu have been derived involving more information of phonon-phonon interactions taken from integration over the first Brillouin zone. Morse potential is assumed to describe the single-pair atomic interaction. N...

  • 24.pdf.jpg
  • Article


  • Authors: Nguyen, Van Hung; Trinh, Thi Hue; Nguyen, Bao Trung; Nguyen, Cong Toan (2017)

  • Anharmonic correlated Debye model is derived for Debye-Waller factors of bcc (body-centered cubic) crystals presented in terms of cumulant expansion up to the fourth order. The many-body effects are taken into account in the present one-dimensional model based on the anharmonic effective potential that includes interactions of absorber and backscatterer atoms with their first shell near neighbors, where Morse potential is assumed to describe the single-pair atomic interaction. Analytical expressions for dispersion relation, correlated Debye frequency and temperature and four first temperature-dependent XAFS (X-ray absorption fine structure) cumulants of bcc crystals have been derived ...

  • 102.pdf.jpg
  • Article


  • Authors: Nguyen, Van Hung; Nguyen, Cong Toan; Hoang, Thi Khanh Giang (2010)

  • Analytical expressions for the ratio of the root mean square fluctuation in atomic positions on the equilibrium lattice positions and the nearest neighbor distance and the mean melting cgryes of bcc binary alloys haye been derived. This melting curve provides information on Lindemann's melting temperatures of binary alloys with respect to any proportion of constituent elements and on their euctectic points. Numerical results for some bcc binary alloys are found to be in agreement with experiment.

  • 115.pdf.jpg
  • Article


  • Authors: Nguyen, Van Hung; Nguyen, Cong Toan; Nguyen, Bao Trung; Ngo, Hoang Giang (2008)

  • Analytical expressions for the Morse potential parameters of diamond crystals have been derived. They contain the energy of sublimation, the compressibility and the lattice constant. Numerical calculations have been carried out for Si and Sn, and the result reflect fundamental calcultion of the anharmonic correlated effective potential parameters have been used for calculation of the anharmonic correlated effective potentials of these crystals in XAFS theory showing clearly anharmonic effects.

  • 132.pdf.jpg
  • Article


  • Authors: Nguyen, Van Hung; Tran, Trung Dung; Nguyen, Cong Toan (2006)

  • A new procedure for description and calculation of th EXAFS (Extended X-ray Absorption Fine Structure) cumulants for fee crystals containing an abitrary number n of dopant atoms have been developed. Analytical expressions for the l 8t, 2nd and 3rd cumulants have been derived.They depend on the number of dopant atoms and approach those derived by anharmonic correlated Einstein model, if all dopant atoms are taken out or replacing all the host atoms. Numerical results for Cu doped by Ni atoms based on the Morse potential show significant dependence of thermodynamic parameters of the substance on the number of dopant atoms and a reasonable agreement with experiment.

  • 209.pdf.jpg
  • Article


  • Authors: Nguyen, Van Hung; Tran, Trung Dung; Nguyen, Cong Toan (2004)

  • A new procedure for description and calculation of the interaction potential and force constants for fee crystals containing an arbitrary number n of impurity atoms have been developed. Analytical expressions for the effective atomic interaction potential, the single-bond and effective spring constants have been derived. They depend on the number of the impurity atoms and approach those derived by using anharmonic correlated Einstein model, if all the impurity atoms are taken out or they replace all the host atoms. Numerical results for Ni doped by Cu atoms show significant changes of the interact on potential and spring constants of the substance if the number of impurity ato...

  • 184.pdf.jpg
  • Article


  • Authors: Nguyen, Van Hung; Ho, Khac Hieu; Nguyen, Cong Toan (2006)

  • A new procedure for calculation and analysis of thermodynamic and correlation effects of bcc crystals under in fluence of dopant atom in the X-ray Absorption Fine Structure (XAFS) has been developed. Analytical expression for the Displacement-displacement Correlation Function (DCF) CR has been derived based on the derived Mean Square Relative Displacement (MSRD) 2 Ơ2 and Mean Square Displacement (MSD) u of bcc crystals containing dopant atom. Numerical calculations have been carried out for Fe doped by w and by Cr atom. They are found to be in good agreement with experiment.

Browsing by Author Nguyen, Cong Toan

Jump to: 0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
or enter first few letters:  
Showing results 1 to 7 of 7
  • 4076-97-8103-1-10-20171016.pdf.jpg
  • Article


  • Authors: Nguyen, Van Hung; Nguyen, Bao Trung; Nguyen, Cong Toan; Ha, Dang Khoa (2017)

  • Debye-Waller factors (DWFs) of metallic Cu (fcc crystal) in X-ray absorption fine structure (XAFS) presented in terms of cumulant expansion have been studied using the anharmonic correlated Debye model (ACDM). This ACDM is derived using the many-body perturbation approach and the anharmonic effective potential that includes the first shell near neighbor contributions to the vibration between absorber and backscatterer atoms. Analytical expressions of three first XAFS cumulants of Cu have been derived involving more information of phonon-phonon interactions taken from integration over the first Brillouin zone. Morse potential is assumed to describe the single-pair atomic interaction. N...

  • 24.pdf.jpg
  • Article


  • Authors: Nguyen, Van Hung; Trinh, Thi Hue; Nguyen, Bao Trung; Nguyen, Cong Toan (2017)

  • Anharmonic correlated Debye model is derived for Debye-Waller factors of bcc (body-centered cubic) crystals presented in terms of cumulant expansion up to the fourth order. The many-body effects are taken into account in the present one-dimensional model based on the anharmonic effective potential that includes interactions of absorber and backscatterer atoms with their first shell near neighbors, where Morse potential is assumed to describe the single-pair atomic interaction. Analytical expressions for dispersion relation, correlated Debye frequency and temperature and four first temperature-dependent XAFS (X-ray absorption fine structure) cumulants of bcc crystals have been derived ...

  • 102.pdf.jpg
  • Article


  • Authors: Nguyen, Van Hung; Nguyen, Cong Toan; Hoang, Thi Khanh Giang (2010)

  • Analytical expressions for the ratio of the root mean square fluctuation in atomic positions on the equilibrium lattice positions and the nearest neighbor distance and the mean melting cgryes of bcc binary alloys haye been derived. This melting curve provides information on Lindemann's melting temperatures of binary alloys with respect to any proportion of constituent elements and on their euctectic points. Numerical results for some bcc binary alloys are found to be in agreement with experiment.

  • 115.pdf.jpg
  • Article


  • Authors: Nguyen, Van Hung; Nguyen, Cong Toan; Nguyen, Bao Trung; Ngo, Hoang Giang (2008)

  • Analytical expressions for the Morse potential parameters of diamond crystals have been derived. They contain the energy of sublimation, the compressibility and the lattice constant. Numerical calculations have been carried out for Si and Sn, and the result reflect fundamental calcultion of the anharmonic correlated effective potential parameters have been used for calculation of the anharmonic correlated effective potentials of these crystals in XAFS theory showing clearly anharmonic effects.

  • 132.pdf.jpg
  • Article


  • Authors: Nguyen, Van Hung; Tran, Trung Dung; Nguyen, Cong Toan (2006)

  • A new procedure for description and calculation of th EXAFS (Extended X-ray Absorption Fine Structure) cumulants for fee crystals containing an abitrary number n of dopant atoms have been developed. Analytical expressions for the l 8t, 2nd and 3rd cumulants have been derived.They depend on the number of dopant atoms and approach those derived by anharmonic correlated Einstein model, if all dopant atoms are taken out or replacing all the host atoms. Numerical results for Cu doped by Ni atoms based on the Morse potential show significant dependence of thermodynamic parameters of the substance on the number of dopant atoms and a reasonable agreement with experiment.

  • 209.pdf.jpg
  • Article


  • Authors: Nguyen, Van Hung; Tran, Trung Dung; Nguyen, Cong Toan (2004)

  • A new procedure for description and calculation of the interaction potential and force constants for fee crystals containing an arbitrary number n of impurity atoms have been developed. Analytical expressions for the effective atomic interaction potential, the single-bond and effective spring constants have been derived. They depend on the number of the impurity atoms and approach those derived by using anharmonic correlated Einstein model, if all the impurity atoms are taken out or they replace all the host atoms. Numerical results for Ni doped by Cu atoms show significant changes of the interact on potential and spring constants of the substance if the number of impurity ato...

  • 184.pdf.jpg
  • Article


  • Authors: Nguyen, Van Hung; Ho, Khac Hieu; Nguyen, Cong Toan (2006)

  • A new procedure for calculation and analysis of thermodynamic and correlation effects of bcc crystals under in fluence of dopant atom in the X-ray Absorption Fine Structure (XAFS) has been developed. Analytical expression for the Displacement-displacement Correlation Function (DCF) CR has been derived based on the derived Mean Square Relative Displacement (MSRD) 2 Ơ2 and Mean Square Displacement (MSD) u of bcc crystals containing dopant atom. Numerical calculations have been carried out for Fe doped by w and by Cr atom. They are found to be in good agreement with experiment.