scholarly journals Anharmonic Contributions to the Vibratory Free Energy of a Lattice

1964 ◽  
Vol 17 (3) ◽  
pp. 269 ◽  
Author(s):  
P Lloyd
Keyword(s):  
Free Energy ◽  
Specific Heat ◽  
Constant Volume ◽  
Bethe Approximation ◽  
Rate Of Increase

The anharmonic contribution to the free energy of a lattice is evaluated by means of a Bethe approximation. The approximation is accurate to within 3% for the model valuated by Maradudin, Flinn, and Coldwell� Horsfall. The anharmonic contribution to the specific heat at constant volume of a model of sodium is evaluated.The specific heat is found to increase as the temperature rises but the rate of increase is lower than the observed value

scholarly journals Thermodynamic properties of CO 2 up to 3000 atmospheres between 25 and 150°C

1937 ◽  
Vol 160 (902) ◽  
pp. 376-384 ◽  
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Total Energy ◽  
Specific Heat ◽  
Interpolation Formula ◽  
Constant Volume ◽  
Present Communication ◽  
Different Temperatures

In previous papers (Michels and Michels 1935; Michels, Michels and Wouters 1935) the results of isotherm measurements on CO 2 and a method for interpolation of the pv values at intermediate temperatures and densities have been published. From the data obtained, the specific heat at constant volume C v , the free energy F , the total energy U , and the entropy S , have been calculated, and these results are given in the present communication. The values of F, U and S at N. T. P. have been taken as zero. The values of C v , F, S and U at a density of 1 Amagat unit ( ρ = 1) have first been calculated for different temperatures. To the values, so obtained, has been added the increase of these quantities by compression. The values of C v at ρ = 1 have been calculated, using the interpolation formula as given by Shilling and Partington (1928).

A First Principles Study of Thermal Properties of Yb-Pnictides (YbX, X= N, P and As) Compounds

2013 ◽  
Vol 665 ◽  
pp. 353-358
Author(s):  
Himadri R. Soni ◽  
Prafulla K. Jha
Keyword(s):  
Free Energy ◽  
Thermal Properties ◽  
Specific Heat ◽  
Internal Energy ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Constant Volume ◽  
Generalized Gradient ◽  
Lattice Specific Heat

Using first principles density functional theoretical calculations within the generalized gradient approximation (GGA), the present paper reports thermal properties such as constant volume lattice specific heat, Gibbs free energy, internal energy, and entropy of Yb-pnictides such as YbN, YbP and YbAs in its rocksalt phase. The variation of lattice specific heat with temperature obeys the classical Dulong-Petits law at high temperature while at low temperature it obeys Debye T3 law. The internal energy, entropy and free energy show a gradual variation with temperature. The specific heat at constant volume at lower temperature increases as going from N to P to As. *Corresponding author Email: [email protected], [email protected] Telephone: +91-278-2422650 Fax: +91-278-2426706

Specific heat of ordered and isotopically disordered lattices

1978 ◽  
Vol 56 (10) ◽  
pp. 1390-1394
Author(s):  
K. P. Srivastava
Keyword(s):  
Specific Heat ◽  
Low Temperatures ◽  
Numerical Study ◽  
Three Dimensional ◽  
Constant Volume ◽  
Nearest Neighbour ◽  
Two Dimensional ◽  
Appreciable Difference ◽  
Substantial Change ◽  
Neighbour Interaction

An extensive numerical study on specific heat at constant volume (Cv) for ordered and isotopically disordered lattices has been made. Cv at various temperatures for ordered and disordered linear and two-dimensional lattices have been compared and no appreciable difference in Cv between these two structures has been observed. Effect of concentration of light atoms on Cv for three-dimensional isotopically disordered lattices has also been shown.In spite of taking next-nearest-neighbour interaction into account, no substantial change in Cv between the ordered and isotopically disordered linear lattices has been found. It is shown that the low lying modes contribute substantially at low temperatures.

THE INHOMOGENEOUS HEISENBERG CHAIN WITH THE INTERACTION OF CLASSICAL AND QUANTUM SPINS

2000 ◽  
Vol 14 (11) ◽  
pp. 1179-1185
Author(s):  
B. I. SADOVNIKOV ◽  
N. G. INOZEMTSEVA ◽  
V. I. INOZEMTSEV
Keyword(s):  
Free Energy ◽  
Specific Heat ◽  
Heisenberg Chain ◽  
Spin Correlations ◽  
Quantum Spins ◽  
Explicit Expressions

The thermodynamics of an inhomogeneous 1D Heisenberg chain with alternating classical and quantum spins is studied. The explicit expressions for the free energy, specific heat, thermal spin correlations and linear susceptibility are found.

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