scholarly journals Effect of the electropositive elements A = Sc, La, and Ce on the microscopic dynamics of AV2Al20

2014 ◽  
Vol 16 (48) ◽  
pp. 27119-27133 ◽  
Author(s):  
Michael Marek Koza ◽  
Andreas Leithe-Jasper ◽  
Erik Sischka ◽  
Walter Schnelle ◽  
Horst Borrmann ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Ab Initio ◽  
Ground State ◽  
Lattice Thermal Conductivity ◽  
Neutron Spectroscopy ◽  
Cage Compound ◽  
Ground State Properties ◽  
Phonon Renormalization ◽  
Microscopic Dynamics

Neutron spectroscopy andab initiocalculations indicate the apparent glass-like lattice thermal conductivityκlof the nano-cage compound ScV2Al20as an effect of phonon renormalization predetermined by the crystal’s ground state properties.

scholarly journals Ground-state properties of Na2IrO3 determined from an ab initio Hamiltonian and its extensions containing Kitaev and extended Heisenberg interactions

2017 ◽  
Vol 96 (5) ◽  
Author(s):  
Tsuyoshi Okubo ◽  
Kazuya Shinjo ◽  
Youhei Yamaji ◽  
Naoki Kawashima ◽  
Shigetoshi Sota ◽  
...  
Keyword(s):  
Ab Initio ◽  
Ground State ◽  
Ground State Properties

scholarly journals Violation of the T−1 Relationship in the Lattice Thermal Conductivity of Mg3Sb2 with Locally Asymmetric Vibrations

Research ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yifan Zhu ◽  
Yi Xia ◽  
Yancheng Wang ◽  
Ye Sheng ◽  
Jiong Yang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Temperature Dependence ◽  
Lattice Thermal Conductivity ◽  
Elevated Temperatures ◽  
Low Frequency ◽  
Strong Temperature Dependence ◽  
Depth Analysis ◽  
Force Profile ◽  
Phonon Renormalization ◽  
Increasing Temperature

Most crystalline materials follow the guidelines of T−1 temperature-dependent lattice thermal conductivity (κL) at elevated temperatures. Here, we observe a weak temperature dependence of κL in Mg3Sb2, T−0.48 from theory and T−0.57 from measurements, based on a comprehensive study combining ab initio molecular dynamics calculations and experimental measurements on single crystal Mg3Sb2. These results can be understood in terms of the so-called “phonon renormalization” effects due to the strong temperature dependence of the interatomic force constants (IFCs). The increasing temperature leads to the frequency upshifting for those low-frequency phonons dominating heat transport, and more importantly, the phonon-phonon interactions are weakened. In-depth analysis reveals that the phenomenon is closely related to the temperature-induced asymmetric movements of Mg atoms within MgSb4 tetrahedron. With increasing temperature, these Mg atoms tend to locate at the areas with relatively low force in the force profile, leading to reduced effective 3rd-order IFCs. The locally asymmetrical atomic movements at elevated temperatures can be further treated as an indicator of temperature-induced variations of IFCs and thus relatively strong phonon renormalization. The present work sheds light on the fundamental origins of anomalous temperature dependence of κL in thermoelectrics.

Ab Initio Theory of the Ground State Properties of Ordered and Disordered Alloys and the Theory of Ordering Processes in Alloys

1986 ◽  
Vol 81 ◽  
Author(s):  
G. Malcolm Stocks ◽  
D.M. Nicholson ◽  
F.J. Pinski ◽  
W.H. Butler ◽  
P. Sterne ◽  
...  
Keyword(s):  
Ab Initio ◽  
Ground State ◽  
Antiphase Boundary ◽  
Functional Theory ◽  
Ordered Structures ◽  
Distant Future ◽  
Disordered Alloys ◽  
Ground State Properties ◽  
Ab Initio Theory ◽  
Method Approach

AbstractWe review some of the advances in the calculation of the electronic structure and energetics of ordered and disordered alloys that hold out the possibility of obtaining, in thenot-too-distant future, an ab initio theory of ordering and phase stability in alloys. In particular, we focus on the calculation of the ground state properties of Ni3Al and discuss the competition between the Li2 and D022 ordered structures. We review the ab initio concentration functional theory of ordering developed by Gyorffy and Stocks and its application to the short-range-ordered solid-solution state in CucPd1-c alloys. Finally, we review the generalized perturbation method approach to calculation of multisite interchange potentials in Ni3Al, Pd3V, and Al3Ti and again discuss L12/D022 competition as well as antiphase boundary energies in Ni3Al.

Ground state properties of cesium dimers from ab initio pseudopotential approaches

1989 ◽  
Vol 90 (12) ◽  
pp. 7306-7312 ◽  
Author(s):  
I. Moullet ◽  
Wanda Andreoni ◽  
P. Giannozzi
Keyword(s):  
Ab Initio ◽  
Ground State ◽  
Ground State Properties

Ab initio investigation of ground-state properties of group-12 fluorides

2014 ◽  
Vol 114 (14) ◽  
pp. 943-951 ◽  
Author(s):  
Susan Torabi ◽  
Lukas Hammerschmidt ◽  
Elena Voloshina ◽  
Beate Paulus
Keyword(s):  
Ab Initio ◽  
Ground State ◽  
Ground State Properties ◽  
Group 12
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