Relationships between the impurity-vacancy binding energy and the core radius, the Debye temperature and the melting temperature in aluminum

1973 ◽  
Vol 44 (4) ◽  
pp. 269-270 ◽  
Author(s):  
O. Takai ◽  
T. Fukusano ◽  
R. Yamamoto ◽  
M. Doyama
1957 ◽  
Vol 35 (4) ◽  
pp. 451-454 ◽  
Author(s):  
M. A. Preston ◽  
J. Shapiro

An attempt has been made to select the core radius and coupling constant of the Lévy potential for the interaction of two nucleons in order to fit the binding energy of the deuteron and the singlet state neutron–proton scattering length. It was found that these two quantities cannot be fitted simultaneously. For any given choice of coupling constant, a somewhat larger core radius is required to fit the deuteron binding energy than is required for the scattering length. This spin dependence of the core radius does not preclude the possibility of a fit to the low energy data with the Lévy potential.


The r. m. s. radius and the binding energy of oxygen 16 are calculated for several different internueleon potentials. These potentials all fit the low-energy data for two nucleons, they have hard cores of differing radii, and they include the Gammel-Thaler potential (core radius 0·4 fermi). The calculated r. m. s. radii range from 1·5 f for a potential with core radius 0·2 f to 2·0 f for a core radius 0·6 f. The value obtained from electron scattering experiments is 2·65 f. The calculated binding energies range from 256 MeV for a core radius 0·2 f to 118 MeV for core 0·5 f. The experimental value of binding energy is 127·3 MeV. The 25% discrepancy in the calculated r. m. s. radius may be due to the limitations of harmonic oscillator wave functions used in the unperturbed system.


1995 ◽  
Vol 163 ◽  
pp. 262-270
Author(s):  
A. M. Cherepashchuk

New spectrophotometric, photometric and polarimetric observations of V444 Cygni confirm the basic conclusion that the WN5 star has a small core radius (rc < 4 R⊙) and a high core temperature (Tc > 60 000 K), which are characteristic of massive helium stars. Values of rc < 3 — 6 R⊙ and Tc > 70 000 — 90 000 K for the core of the WN7 star in the Cygnus X-3 system agree well with this conclusion. A clumping structure of WR winds is suggested. X-ray observations of colliding winds in WR+O binaries suggest radial expansion and anomalous chemical composition of WR winds.


2005 ◽  
Vol 12 (02) ◽  
pp. 227-232 ◽  
Author(s):  
S. B. GESARI ◽  
B. L. IRIGOYEN ◽  
A. JUAN

We have studied the effect of hydrogen on the cohesion of two types of dislocation in bcc iron at an atomistic level, using the atom superposition and electron delocalization molecular orbital (ASED-MO) method. The most stable positions for one hydrogen at each dislocation core were determined. It was found that the total energy of the cluster decreases when the hydrogen is located at the core. This effect is higher in a mixed dislocation in accordance with the experimental data. The computed results show that hydrogen is a strong embrittler and that a decrease in the Fe–Fe overlap population plays a dominant role in the decohesion of the crystal structure.


2015 ◽  
Vol 17 (37) ◽  
pp. 24349-24355 ◽  
Author(s):  
Roberto Carlos Salvarezza ◽  
Pilar Carro

DFT calculations show that the core level shift (CLS) of the S 2p binding energy of thiol and sulfur atoms on different thiol–Pd(111) surfaces strongly depends on the adsorbed or subsurface state of sulfur atoms.


2012 ◽  
Vol 2012 ◽  
pp. 1-34 ◽  
Author(s):  
D. S. Sankar ◽  
Yazariah Yatim

Pulsatile flow of blood in narrow tapered arteries with mild overlapping stenosis in the presence of periodic body acceleration is analyzed mathematically, treating it as two-fluid model with the suspension of all the erythrocytes in the core region as non-Newtonian fluid with yield stress and the plasma in the peripheral layer region as Newtonian. The non-Newtonian fluid with yield stress in the core region is assumed as (i) Herschel-Bulkley fluid and (ii) Casson fluid. The expressions for the shear stress, velocity, flow rate, wall shear stress, plug core radius, and longitudinal impedance to flow obtained by Sankar (2010) for two-fluid Herschel-Bulkley model and Sankar and Lee (2011) for two-fluid Casson model are used to compute the data for comparing these fluid models. It is observed that the plug core radius, wall shear stress, and longitudinal impedance to flow are lower for the two-fluid H-B model compared to the corresponding flow quantities of the two-fluid Casson model. It is noted that the plug core radius and longitudinal impedance to flow increases with the increase of the maximum depth of the stenosis. The mean velocity and mean flow rate of two-fluid H-B model are higher than those of the two-fluid Casson model.


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