scholarly journals Thermodynamics of technetium: reconciling theory and experiment using density functional perturbation analysis

2015 ◽  
Vol 44 (28) ◽  
pp. 12735-12742 ◽  
Author(s):  
Philippe F. Weck ◽  
Eunja Kim
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Heat Capacity ◽  
Thermal Expansion ◽  
Thermodynamic Properties ◽  
Perturbation Analysis ◽  
Lattice Dynamics ◽  
Density Functional ◽  
Functional Theory ◽  
Theory And Experiment

The structure, lattice dynamics and thermodynamic properties of bulk technetium were investigated within the framework of density functional theory. The predicted thermal expansion and isobaric heat capacity are in excellent agreement with available experimental data.

Theoretical Investigations on Elastic and Thermodynamic Properties of CdTe

2012 ◽  
Vol 534 ◽  
pp. 192-196
Author(s):  
Yu Hong Huang ◽  
Wan Qi Jie ◽  
Gang Qiang Zha
Keyword(s):  
Density Functional Theory ◽  
Heat Capacity ◽  
Thermal Expansion ◽  
Thermodynamic Properties ◽  
Density Functional ◽  
Debye Model ◽  
Extreme Conditions ◽  
Functional Theory ◽  
Opposite Case ◽  
Theoretical Investigations

The elastic and thermodynamic properties of CdTe are studied under a pressure up to 8GPa and at a temperature range of 0~900K, by density functional theory as well as quasi-harmonic Debye model. The calculated bulk modulus B and its derivative B' are consistent with the values fitted according to Debye model, which confirms the applicability of Debye model to CdTe. Heat capacity Cv , Grüneisen parameter and thermal expansion coefficient decrease with pressure, but increase with temperature. It is an opposite case for Debye temperature . The results may be instructive for CdTe to be applied in extreme conditions.

scholarly journals Thermodynamics of Uranium Tri-Iodide from Density-Functional Theory

2020 ◽  
Vol 10 (11) ◽  
pp. 3914
Author(s):  
Per Söderlind ◽  
Aurélien Perron ◽  
Emily E. Moore ◽  
Alexander Landa ◽  
Tae Wook Heo
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Heat Capacity ◽  
Density Functional ◽  
Thermodynamic Assessment ◽  
Harmonic Approximation ◽  
Metallic System ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation

Density-functional theory (DFT) is employed to investigate the thermodynamic and ground-state properties of bulk uranium tri-iodide, UI3. The theory is fully relativistic and electron correlations, beyond the DFT and generalized gradient approximation, are addressed with orbital polarization. The electronic structure indicates anti-ferromagnetism, in agreement with neutron diffraction, with band gaps and a non-metallic system. Furthermore, the formation energy, atomic volume, crystal structure, and heat capacity are calculated in reasonable agreement with experiments, whereas for the elastic constants experimental data are unavailable for comparison. The thermodynamical properties are modeled within a quasi-harmonic approximation and the heat capacity and Gibbs free energy as functions of temperature agree with available calculation of phase diagram (CALPHAD) thermodynamic assessment of the experimental data.

Study of Thermodynamic Properties of Superhard w-BC2N

2013 ◽  
Vol 750-752 ◽  
pp. 1141-1145
Author(s):  
Ai Ling Ding ◽  
Feng Li ◽  
Chun Mei Li ◽  
Jing Ao ◽  
Zhi Qian Chen
Keyword(s):  
Density Functional Theory ◽  
Heat Capacity ◽  
Thermodynamic Properties ◽  
Density Functional ◽  
Local Density ◽  
Density Functional Theory Method ◽  
Debye Model ◽  
Theory Method ◽  
Density Approximation ◽  
Functional Theory

We investigate the thermodynamic properties of superhard w-BC2N by using ab initio plane-wave pseudopotential density functional theory method within local density approximation (LDA). Through the quasi-harmonic Debye model, we investigate the thermodynamic properties of w-BC2N. The variation of the thermal expansion, the heat capacity and the Gruneisen parameter γ with pressure P and temperature T, and many other thermodynamic parameters of w-BC2N are obtained systematically.

Ab initio modelling of methane hydrate thermophysical properties

2016 ◽  
Vol 18 (15) ◽  
pp. 10320-10328 ◽  
Author(s):  
Z. M. Jendi ◽  
P. Servio ◽  
A. D. Rey
Keyword(s):  
Density Functional Theory ◽  
Heat Capacity ◽  
Thermal Expansion ◽  
Ab Initio ◽  
Thermal Expansion Coefficient ◽  
Elastic Constants ◽  
Thermophysical Properties ◽  
Methane Hydrate ◽  
Density Functional ◽  
Functional Theory

Using density functional theory, the second-order elastic constants, heat capacity, compressibility, and thermal expansion coefficient of methane hydrate were calculated.

scholarly journals Electronic and thermal properties of LuNi2B2C under pressure

2020 ◽  
Vol 48 (5-6) ◽  
pp. 469-479
Author(s):  
LILI LIU ◽  
YUHAN JIANG ◽  
LIWAN CHEN ◽  
YOUCHANG JIANG ◽  
YELU HE ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Heat Capacity ◽  
Thermal Expansion ◽  
Perturbation Theory ◽  
Thermal Properties ◽  
Density Functional ◽  
Constant Pressure ◽  
Functional Theory ◽  
Density Functional Perturbation Theory ◽  
Temperature And Pressure

The electronic and thermal properties of LuNi2B2C were studied by performing density-functional theory (DFT) and density functional perturbation theory (DFPT). No virtual frequencies appear on the phonon spectrum, indicating that LuNi2B2C is dynamically stable in the tetragonal structure up to 30 GPa. The density of states at Fermi energy EF is nonzero and falls on the sharp peak, which is why LuNi2B2C has a high superconducting temperature. Moreover, the temperature and pressure dependences of bulk modulus, heat capacity at constant pressure and thermal expansion coefficient in a wide temperature (0-900 K) and pressure (0-30 GPa) ranges are presented in this study.

Theoretical determination of the structures of CaSiO3 perovskites

2006 ◽  
Vol 62 (6) ◽  
pp. 1025-1030 ◽  
Author(s):  
Razvan Caracas ◽  
Renata M. Wentzcovitch
Keyword(s):  
Crystal Structure ◽  
Experimental Data ◽  
Density Functional Theory ◽  
Density Functional ◽  
Theoretical Determination ◽  
Functional Theory ◽  
Starting Point ◽  
Atomic Coordinates ◽  
The Ideal

Density functional theory is used to determine the possible crystal structure of the CaSiO3 perovskites and their evolution under pressure. The ideal cubic perovskite is considered as a starting point for studying several possible lower-symmetry distorted structures. The theoretical lattice parameters and the atomic coordinates for all the structures are determined, and the results are discussed with respect to experimental data.

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