scholarly journals Удельная теплоемкость и температура Дебая сжатого кристаллического неона в модели деформируемых атомов

2020 ◽  
Vol 62 (12) ◽  
pp. 2129
Author(s):  
Е.П. Троицкая ◽  
Е.А. Пилипенко ◽  
Е.Е. Горбенко

The thermodynamic properties of compressed neon crystal has been theoretically investigated within the ab initio approach taking into account the many-body interaction in the model of deformable atoms. In the short-range repulsive potential, along with the three-body interaction associated with the overlap of the electron shells of atoms, deformation of electron shells of dipole-type atoms is taken into account in the pair and three-particle approximations. The specific heat capacities and the Debye temperature in a wide pressure and temperature range have been calculated using the dynamic matrix constructed with the ab initio short-range repulsive potential and integration over the mean value points of the Chadi–Kohen method. It is shown that the contributions of three-body forces associated with both the overlap of the electron shells of atoms and the deformation of the electron shells increase the value of specific heat of compressed neon face-centered cubic crystals even at zero pressure. The temperature dependences are obtained in good agreement with the available experiment data and calculation results obtained by other researchers.

2019 ◽  
Vol 61 (10) ◽  
pp. 1890
Author(s):  
Е.П. Троицкая ◽  
Е.А. Пилипенко ◽  
Е.Е. Горбенко

A dynamic matrix of rare-gas crystals is constructed on the basis of a nonempirical short-range repulsion potential taking into account the three-body interaction and dipole-type deformation of the electron shells of atoms in the two- and three-body approximations in the model of deformable and polorizable atoms. Ab initio calculations of the phonon energy for compressed rare-gas crystals were performed at the two and ten mean-value points of the Chadi-Cohen method in a wide pressure range. It is shown that the contribution of three-body forces associated with the overlap of the electron shells of nearest-neighbor atoms in the phonon frequencies is small against the background of pair interaction, even at high pressure and most noticeable in Xe. The contribution of the deformation of the electron shells in the two- and three-body approximations is different for the different mean-value points and increases with increasing pressure. Comparison of the zero-point energy calculated by the Chadi-Cohen method for compressed crystals of the Ne–Xe series was performed with the available experiment at p=0 and the results of other authors.


1996 ◽  
Vol 211 (1-3) ◽  
pp. 179-189 ◽  
Author(s):  
Peter Wind ◽  
Inge Røeggen

2018 ◽  
Vol 60 (1) ◽  
pp. 151
Author(s):  
Е.А. Пилипенко ◽  
Е.П. Троицкая ◽  
Е.Е. Горбенко

AbstractNonempirical equations of state of compressed rare gas crystals Ne, Ar, Kr, and Xe are studied on the basis of the earlier-obtained ab initio adiabatic potential. The paired and three-body short-range repulsive potentials are calculated by the Hartree–Fock method in the basis of localized functions with their exact mutual orthogonalization and do not contain experimentally determined parameters. The theory is compared with the experiment and results of calculations by other authors. Analysis of the proposed equations of state for large compressions has shown the importance of taking into account the three-body interaction and the terms of the higher order in the overlap integral in compressed neon and the sufficiency of the quadratic approximation in the orthogonalization of functions in heavy rare gas crystals.


2019 ◽  
Vol 61 (1) ◽  
pp. 154
Author(s):  
Е.П. Троицкая ◽  
Е.А. Пилипенко ◽  
Е.Е. Горбенко

AbstractOn the basis of ab initio calculations of the phonon frequencies of compressed rare-gas crystals in the model of deformable and polarizable atoms, dynamic instability of the fcc lattice of these crystals is studied. In addition to the earlier-considered three-body interaction, which is associated with the overlapping of the electron shells of atoms, the short-range potential includes three-body forces caused by the mutual deformation of the electron shells of neighboring atoms. It is shown that the allowance for the deformation of the dipole-type electron shells of atoms in the pair and three-body approximations leads to softening of the critical vibrations and absolute instability of the fcc lattice at pressures higher than the critical values, p > p _ c . For light crystals of Ne and Ar under compressions of 0.76 ( p _ c = 422 GPa) and 0.71 ( p _ c = 405 GPa), respectively, the softening of the longitudinal mode is observed at the boundary of the Brillouin zone at the point L ; for heavy crystals of Kr and Xe under compressions of 0.686 ( p _ c = 240 GPa) and 0.605 ( p _ c = 88 GPa), the transverse mode T _1 is softened in the direction Σ. The behavior of second-order Fuchs elastic moduli of compressed rare-gas crystals is discussed.


2019 ◽  
Vol 1 (3) ◽  
Author(s):  
Simon Panyella Pedersen ◽  
K. S. Christensen ◽  
N. T. Zinner

2021 ◽  
pp. 105281
Author(s):  
Md Sanam Suraj ◽  
Rajiv Aggarwal ◽  
Md Chand Asique ◽  
Amit Mittal ◽  
Mamta Jain ◽  
...  

2003 ◽  
Vol 118 (6) ◽  
pp. 2731 ◽  
Author(s):  
Jacek Jakowski ◽  
Grzegorz Chałasiński ◽  
S. M. Cybulski ◽  
M. M. Szczȩśniak

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