Application of Houston's Method to the Sum of Plane Waves over the Brillouin Zone. I. Simple‐Cubic and Face‐Centered‐Cubic Lattices

1966 ◽  
Vol 7 (1) ◽  
pp. 139-147 ◽  
Author(s):  
Maria Miasek
1962 ◽  
Vol 40 (9) ◽  
pp. 1153-1165 ◽  
Author(s):  
S. Ganesan ◽  
R. Srinivasan

In evaluating integrals over the Brillouin zone by Houston's method, a normalization factor has to be used. A wave-vector-dependent normalization factor nj(q + Δq/2) is calculated by equating the volume common to a spherical shell of radius q and thickness Δq and the simple cubic Brillouin zone to the expression given by a j-direction Houston method. Some sample integrals are evaluated using this (GS) normalization procedure and Horton and Schiff's (HS) normalization procedure, originally developed for face-centered cubic lattices. The superiority of the GS method, especially with highly anisotropic functions, is demonstrated. From an evaluation of the moments of the frequency distribution function in a simple cubic lattice for various values of the anisotropy parameter, it is concluded that, when high accuracy is desired, the GS procedure is applicable over a wider range of anisotropy parameter than the HS procedure. The θ–T curve calculated by using the correct normalization procedure in a simple cubic lattice is in good agreement with that calculated by Blackman's method.


1972 ◽  
Vol 50 (23) ◽  
pp. 2991-2996 ◽  
Author(s):  
M. F. Collins ◽  
V. K. Tondon

The ground state energy, spin-wave energy, and sublattice magnetization have been calculated for a Heisenberg antiferromagnet at the absolute zero of temperature. The treatment extends the earlier work of Anderson, Kubo, and Oguchi to apply for any two-sublattice antiferromagnet with arbitrary range of interaction. It is shown that for each exchange interaction there is a different characteristic correction term to the energies. Explicit calculations are made of these terms for the simple cubic, body-centered cubic, and face-centered cubic lattices, with both first- and second-neighbor interactions. Applications are also made to NiO and MnO. An extra term in the magnetization series beyond that given by earlier workers is derived.


2020 ◽  
Vol 102 (4) ◽  
Author(s):  
Vitaly A. Kuzkin ◽  
Sergei D. Liazhkov

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 182 ◽  
Author(s):  
Bing Li ◽  
Jinbo Zhang ◽  
Zhipeng Yan ◽  
Meina Feng ◽  
Zhenhai Yu ◽  
...  

Using in situ high-pressure Raman spectroscopy and X-ray diffraction, the polymerization and structure evaluation of C60 were studied up to 16 GPa at room temperature. The use of an 830 nm laser successfully eliminated the photo-polymerization of C60, which has interfered with the pressure effect in previous studies when a laser with a shorter wavelength was used as excitation. It was found that face-centered cubic (fcc) structured C60 transformed into simple cubic (sc) C60 due to the hint of free rotation for the C60 at 0.3 GPa. The pressure-induced dimerization of C60 was found to occur at about 3.2 GPa at room temperature. Our results suggest the benefit and importance of the choice of the infrared laser as the excitation laser.


1968 ◽  
Vol 11 (12) ◽  
pp. 56-63
Author(s):  
V. P. Fadin ◽  
Yu. A. Khon ◽  
V. E. Panin

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