Anharmonic

The derived temperature dependences of the peak intensities, separations and half-widths of the separate spectral peaks in the A-band phonon progressions indicate the different trends for vibration-free zero-phonon electronic transition and vibration-related lower-energy electronic transitions to high vibrational levels of the ground electronic state – lower thermal damping and more softened phonon for the zero-phonon transition, also implying the extended defect origin of the A-band photoluminescence.

9p dianmotminh02 03-05-2024 3 1   Download

Target of thesis: To develop a method that can simplify the determination of the thermodynamic parameters and XAFS spectra which base on the second-order cumulant only. In particular, this method can be applied for both theoretical calculations and experimental measurements in the XAFS method.

27p extraenglish 24-05-2021 31 5   Download

The analytic expressions of thermodynamic quantities such as the Helmholtz free energy, the internal energy, the entropy, the molar heat capacity at constant volume for molecular cryocrystals of N2 type with face-centered cubic (FCC) and hexagonal close-packed (HCP) structures in harmonic, classical and anharmonic approximations are obtained by combining the statistical moment method (SMM) and the self-consistent field method (SCFM).

10p tamynhan5 10-12-2020 12 1   Download

Some thermodynamic quantities of ZrxCe1-xO2/CeO2 systems are investigated by using the moment method in statistical dynamics taking into account the anharmonicity effects of lattice vibrations. The analytic expression of the Gibbs free energy, Helmholtz free energy, and specific heats at the constant volume of ZrxCe1-xO2/CeO2 systems are obtained.

11p tamynhan9 02-12-2020 12 1   Download

The coefficients of thermal expansion of thin metal film with face-centered cubic structure at zero pressure are investigated using the statistical moment method (SMM), including the anharmonic effects of thermal lattice vibration. The Helmholtz free energy, mean-square atomic displacement and linear thermal expansion coefficients are derived in closed analytic forms in terms of the power moments of the atomic displacement.

8p tamynhan8 04-11-2020 14 1   Download

To develop a method that can simplify the determination of the thermodynamic parameters and XAFS spectra which base on the second-order cumulant only. In particular, this method can be applied for both theoretical calculations and experimental measurements in the XAFS method.

27p trinhthamhodang7 27-08-2020 34 3   Download

Analytical expressions for the anharmonic effective potential, local force constant, Displacement-displacement Correlation Function (DCF) CR and Debye-Waller factor described by the Mean Square Relative Displacement (MSRD) σ2 and by the Mean Square Displacement (MSD) u2of bcc crystals in the X-ray Absorption Fine Structure (XAFS) have been derived. The effective interatomic potential of the system has been considered by taking into account the influences of nearest atomic neighbors, and it contains the Morse potential characterizing the interaction of each pair of atoms.

8p 12120609 01-06-2020 14 2   Download

We have investigated the thermodynamic properties of the cubic zirconia ZrO2 using the statistical moment method in the statistical physics. The free energy, thermal lattice expansion coefficient, specific heats at the constant volume and those at the constant pressure, CV and CP , are derived in closed analytic forms in terms of the power moments of the atomic displacements.

16p 12120609 01-06-2020 10 1   Download

High-order anharmonic effective potentials and four EXAFS cumulants have been studied taking into account the influence of the nearest neighbors of absorbing and backscattering atoms by Analytical expressions of th quantum potential expanded in the fourth order which influences from the 4thcumulants. Numerical results for Ni are found to be in good a experiment and the classical theory.

6p advanger2 06-05-2018 35 0   Download

Anharmonic effective potential, effective local force constant, thermal expansion coefficient, three leading cumulants, and EXAFS (Extended X-ray Absorption Fine Structure) of hcp crystals have been studied. Analytical expressions for these quantities have been derived. Numerical calculations have been carried out for Zn and Cd. They show a good agreement with experiment results measured at HASYLAB (DESY, Germany) and unnegligible anharmonic effects in the considered quantities.

7p tuanlocmuido 19-12-2012 51 2   Download

A new procedure for calculation and analysis of XAFS (X-ray Absorption Fine Structure) cumulants of hcp crystals containing dopant atom has been derived based on quantum statistical theory with generalized anharmonic correlated Einstein model. Analytical expressions for effective local force constants, correlated Einstein frequency and temperature, first cumulant or net thermal expansion, second cumulant or Debye Waller factor and third cumulant of hcp crystals containing dopant atom have been derived.

7p tuanlocmuido 19-12-2012 38 3   Download