Comparison of Certain Local Pseudopotentials and a New Proposal

2013 ◽  
Vol 665 ◽  
pp. 70-73
Author(s):  
Smruti J. Patel ◽  
A.Y. Vahora ◽  
B.Y. Thakore ◽  
Ashvin R. Jani
Keyword(s):  
Phonon Dispersion ◽  
Liquid Metals ◽  
Form Factors ◽  
Model Potential ◽  
Test Case ◽  
Nearest Neighbour ◽  
Core Radius ◽  
Phonon Dispersion Curves ◽  
Neighbour Distance

A new proposal of a local pseudopotential is put forwarded here depending on the concept of extended core radius in which half of the nearest neighbour distance is treated as effective core radius. There is no input of any property for fitting this parameter in this formalism. This pseudopotential is found to satisfy all the necessary requirements for applications. With this model potential we have evaluated the form factors for several bcc, fcc and hcp metals and achieved excellent agreement with previous results. On the same footing, we have examined other 14 local pseudo potentials also and on the basis of the comparison, the presently proposed pseudopotential is found to be much better. As a test case study, we have evaluated phonon dispersion curves of some liquid metals, viz. Na (Z = 1), Mg (Z = 2), Al (Z= 3) and Pb (Z = 4) and obtained quite satisfactory results.

Article

1998 ◽  
Vol 76 (2) ◽  
pp. 143-151
Author(s):  
J S Ononiwu
Keyword(s):  
Lattice Dynamics ◽  
Alkaline Earth ◽  
Phonon Dispersion ◽  
Earth Metal ◽  
Model Potential ◽  
Dispersion Curves ◽  
The Body ◽  
Symmetry Direction ◽  
Normal Ordering ◽  
Phonon Dispersion Curves

A phenomenological one-parameter model potential that includes sp-d hybridization and core--core exchange contributions is used to calculate the phonon dispersion curves in the lattice dynamics of the body-centered cubic alkaline-earth metal, barium. There is good overall agreement between theory and experiment, and in particular, in the [xi00] direction we obtained frequencies of the transverse dispersion curves that are lower than those of the longitudinal dispersion curves along the [100] symmetry direction thereby restoring the normal ordering of the branches.PACS Nos.: 63.20D

scholarly journals Systematic Stakeholder Inclusion in Digital Agriculture: A Framework and Application to Canada

2021 ◽  
Vol 13 (12) ◽  
pp. 6879
Author(s):  
Hassan P. Ebrahimi ◽  
R. Sandra Schillo ◽  
Kelly Bronson
Keyword(s):  
Agricultural Sector ◽  
Food System ◽  
News Article ◽  
Test Case ◽  
Stakeholder Groups ◽  
Research And Innovation ◽  
Article Analysis ◽  
Digital Agriculture ◽  
Responsible Research

This study provides a model that supports systematic stakeholder inclusion in agricultural technology. Building on the Responsible Research and Innovation (RRI) literature and attempting to add precision to the conversation around inclusion in technology design and governance, this study develops a framework for determining which stakeholder groups to engage in RRI processes. We developed the model using a specific industry case study: identifying the relevant stakeholders in the Canadian digital agriculture ecosystem. The study uses literature and news article analysis to map stakeholders in the Canadian digital agricultural sector as a test case for the model. The study proposes a systematic framework which categorises stakeholders into individuals, industrial and societal groups with both direct engagement and supportive roles in digital agriculture. These groups are then plotted against three levels of impact or power in the agri-food system: micro, meso and macro.

ELASTIC PROPERTIES OF STRAINED FCC AND HCP IRON

1993 ◽  
Vol 07 (01n03) ◽  
pp. 207-211
Author(s):  
T. KRAFT ◽  
M. METHFESSEL ◽  
M. VAN SCHILFGAARDE ◽  
M. SCHEFFLER
Keyword(s):  
Energy Cost ◽  
Interplanar Distance ◽  
Orbital Method ◽  
Full Potential ◽  
Local Spin Density Approximation ◽  
Nearest Neighbour ◽  
Density Approximation ◽  
Neighbour Distance ◽  
Large Lattice ◽  
Fcc Phase

Using the full-potential linear muffin-tin orbital method within the local spin-density approximation we analyse the influence of the nearest neighbour distance on fcc(111) or hcp(0001) iron layers. The LDA-LSDA error in describing ferromagnetic phases is determined to be at least 15 mRy/atom. As a consequence of this error, our calculations favour paramagnetic ground states. In this sense, the reported results have some model character. However, our analysis of the elastic energy cost under distortions should hold for transition metals in general. Allowing relaxations of the interplanar distance the fcc phase can become energetically favourable over the hcp phase at large lattice mismatches. The main reason for this behaviour is the enhanced stiffness of the hcp interplanar bonds due to the shortening of the axial c/a ratio.

The crystal dynamics of cuprous halides

1982 ◽  
Vol 60 (11) ◽  
pp. 1589-1594 ◽  
Author(s):  
Manvir S. Kushwaha
Keyword(s):  
Phonon Dispersion ◽  
Characteristic Temperature ◽  
Force Model ◽  
Phonon Dispersion Curves ◽  
Debye Characteristic Temperature ◽  
Zinc Blende ◽  
Crystal Dynamics ◽  
Bond Bending ◽  
Dynamical Description ◽  
Good Agreement

The lattice dynamics of cuprous halides have been thoroughly investigated by means of an 8-parameter bond-bending force model (BBFM), recently developed and applied successfully to study phonons in various II–VI and III–V compound semiconductors having zinc-blende (ZB) structure. The application of BBFM is made to calculate the phonon dispersion relations, phonon density of states, and temperature variation of the Debye characteristic temperature [Formula: see text] of CuCl, CuBr, and CuI. The room-temperature neutron scattering measurements for phonon dispersion curves along three principal symmetry directions and calorimetric experimental data for the Debye characteristic temperature have been used to check the validity of BBFM for the three crystals. The overall good agreement between theoretical and experimental results supports its use as an appropriate model for the dynamical description of ZB crystals.

Phonon Dispersion Curves of aBC3Honeycomb Epitaxial Sheet

2004 ◽  
Vol 93 (17) ◽  
Author(s):  
H. Yanagisawa ◽  
T. Tanaka ◽  
Y. Ishida ◽  
M. Matsue ◽  
E. Rokuta ◽  
...  
Keyword(s):  
Phonon Dispersion ◽  
Dispersion Curves ◽  
Phonon Dispersion Curves
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