scholarly journals EFFECT OF DISORDER ON THE INTERACTING FERMI GASES IN A ONE-DIMENSIONAL OPTICAL LATTICE

2008 ◽  
Vol 22 (25n26) ◽  
pp. 4500-4510 ◽  
Author(s):  
XIANLONG GAO ◽  
M. POLINI ◽  
M. P. TOSI ◽  
B. TANATAR
Keyword(s):  
Density Functional ◽  
Cold Atoms ◽  
Local Density ◽  
Fermi Gases ◽  
Functional Theory ◽  
One Dimensional ◽  
Exchange Correlation ◽  
Site Disorder ◽  
Interesting Compound ◽  
Main Effects

Interacting two-component Fermi gases loaded in a one-dimensional (1D) lattice and subjected to a harmonic trapping potential exhibit interesting compound phases in which fluid regions coexist with local Mott-insulator and/or band-insulator regions. Motivated by experiments on cold atoms inside disordered optical lattices, we present a theoretical study of the effects of a correlated random potential on these ground-state phases. We employ a lattice version of density-functional theory within the local-density approximation to determine the density distribution of fermions in these phases. The exchange-correlation potential is obtained from the Lieb-Wu exact solution of Fermi-Hubbard model. On-site disorder (with and without Gaussian correlations) and harmonic trap are treated as external potentials. We find that disorder has two main effects: (i) it destroys the local insulating regions if it is sufficiently strong compared with the on-site atom-atom repulsion, and (ii) it induces an anomaly in the inverse compressibility at low density from quenching of percolation. For sufficiently large disorder correlation length the enhancement in the inverse compressibility diminishes.

Theoretical Study of Atoms Filled in Carbon Nanotubes

2016 ◽  
Vol 13 (10) ◽  
pp. 6974-6977
Author(s):  
Shuwen Cui ◽  
Weiwei Liu ◽  
Xiaosong Wang
Keyword(s):  
Carbon Nanotubes ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Study ◽  
Local Density ◽  
First Principles Calculations ◽  
Functional Theory ◽  
One Dimensional ◽  
Local Density Functional Theory ◽  
Foreign Materials

The nano-sized quasi-one dimensional hollow cores of carbon nanotubes make it possible for them to be filled with and wetted by foreign materials. With C, S and Se atoms as example, we have studied the filling and wetting of these atoms into carbon nanotubes from local density functional theory in first principles calculations. The results suggest that the effect of nanotube length is negligible when it exceeds 3.6 Å, there is a relation between nanotube diameter and filling and wetting. Our studies would be important implications for the further use of carbon nanotubes.

Ab intio Investigations of Lattice Parameters in ZnMgO Alloys

2009 ◽  
Vol 1201 ◽  
Author(s):  
Markus Heinemann ◽  
Marcel Giar ◽  
Christian Heiliger
Keyword(s):  
Density Functional ◽  
Local Density ◽  
Density Functional Theory Calculations ◽  
Lattice Parameters ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Lattice Constants ◽  
Exchange Correlation ◽  
Vegard’S Law ◽  
Constant Unit

AbstractWe perform density functional theory calculations to determine equilibrium lattice parameters of wurtzite Zn1-xMgxO alloys for Mg concentrations x ranging from 0 to 31.25 %. We use the local density approximation (LDA) as well as the generalized gradient approximation (GGA) for the exchange correlation functional. For the lattice constants a and c we find a deviation from Vegard's law and a constant unit cell volume independent of the Mg concentration.

Research on the Elastic Property of Three New Superhard Materials

2013 ◽  
Vol 302 ◽  
pp. 165-169
Author(s):  
Feng Li ◽  
Qun Hui ◽  
Jing Ao ◽  
Jin Wang ◽  
Chun Mei Li ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Correlation Effect ◽  
Superhard Materials ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Spatial Anisotropy ◽  
Plane Wave Method ◽  
Exchange Correlation

In this thesis, elastic properties of three BCN superhard materials with different structures are computed by using CASTEP software developed according to the first principles which are based on density functional theory (DFT) and plane wave method. CA-PZ of local density approximation (LDA) and PBE of generalized gradient approximation (GGA) are adopted to describe the exchange-correlation effect between electrons. The results are compared with other findings and c-BN data. Through analysis, it is found that the spatial anisotropy do exist in the Young's modulus of single crystals all three BCN compounds.

First-principles investigation of the vibrational properties of 3-tert-butylcyclohexene

Open Physics ◽  
2010 ◽  
Vol 8 (5) ◽  
Author(s):  
Katalin Gaál-Nagy
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Vibrational Properties ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Density Functional Perturbation Theory ◽  
Characteristic Modes ◽  
Correlation Potential

AbstractI present a first-principles investigation of the vibrational properties of the chiral molecule 3-tert-butylcyclohexene. The vibrational density of states (vDOS) of the two existing conformers has been calculated ab initio within the framework of density-functional theory and density-functional perturbation theory, using both the local-density approximation and the generalized-gradient approximation for the exchange-correlation potential. The vDOS of the two conformers are very similar. The vDOS has been investigated with respect to contributions of the cyclohexene ring and the tert-butyl group and also regarding the localization of vibrational modes. Additionally, the eigendisplacements of characteristic modes of 3-tert-butylcyclohexene have been analyzed.

MEAN FIELD APPROACH TO THE GAP OF A MODEL INTERACTING SYSTEM

1988 ◽  
Vol 02 (01) ◽  
pp. 87-101
Author(s):  
KAJOLI BANERJEE ◽  
VIJAY A. SINGH ◽  
G. R. BHAT
Keyword(s):  
Density Functional ◽  
Local Density ◽  
Mean Field ◽  
Functional Theory ◽  
One Dimensional ◽  
Coulomb Term ◽  
The Density Functional Theory ◽  
The Mean ◽  
Transfer Term ◽  
Mean Field Approximations

The well-known local density approximation severely underestimates the gap of insulating materials. We undertake a study of an infinite one-dimensional model interacting system where the gap is known exactly. We use variational procedures, similar in spirit to Hohenberg and Kohn's derivation of the density functional theory. The mean field approximations so obtained are used to calculate the gap in the eigenspectrum. The gap is found to be systematically underestimated for realistic values of the parameters (u/t ≤ 4 where u is the Coulomb term and t, the transfer term). For u/t > 4, the approximate gap is in close agreement with the exact gap. The underestimation of the gap is investigated with respect to the discontinuity in the effective potential.

The structural and elastic properties of TMB4(TM =V,Cr,Mn) under pressure: A first-principles study

2014 ◽  
Vol 28 (29) ◽  
pp. 1450202 ◽  
Author(s):  
Xiao-Long Wu ◽  
Xiao-Lin Zhou ◽  
Jing Chang
Keyword(s):  
Elastic Properties ◽  
Density Functional ◽  
Mechanical Stability ◽  
Local Density ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Wide Pressure Range ◽  
G Ratio ◽  
Wide Pressure

The structural and elastic properties of 3d transition metal tetraboride TM B4(TM = V , Cr , Mn ) have been studied by using density functional theory (DFT) within the local density approximation (LDA) and generalized gradient approximation (GGA) for exchange-correlation function. Our results are in agreement well with available experimental data and previous theoretical studies. The full elastic constants and bulk shear modulus of TM B4(TM = V , Cr , Mn ) are obtained in the wide pressure range. Results indicated that these phases of TM B4(TM = V , Cr , Mn ) are strongly pressure dependent. And the CrB4in Immm structure is the most ultraincompressible among the considered phases at 0 GPa. By the mechanical stability criteria, it is predicted that these phases of TM B4(TM = V , Cr , Mn ) compounds are stable up to 100 GPa. In addition, the calculated B/G ratio indicated that all the structures of TM B4(TM = V , Cr , Mn ) possess brittle nature in the range of pressure from 0 GPa to 100 GPa except the Pnnm structure of MnB4, which is higher than 1.75, indicating that the Pnnm structure of MnB4is prone to ductility when the pressure is above 73 GPa.

The first principle study of electronic and optical properties in rhombohedral BiAlO3

2016 ◽  
Vol 30 (03) ◽  
pp. 1650006 ◽  
Author(s):  
Geoffrey Tse ◽  
Dapeng Yu
Keyword(s):  
Density Functional ◽  
Lattice Structure ◽  
Local Density ◽  
Lattice Parameter ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Visualization Software ◽  
Material Studio ◽  
Local Density Approximations ◽  
Phonon Properties

We studied the crystal structure of perovskite BiAlO3 using ab initio density functional theory (DFT) calculations. Using the atomic positions given by the previous literature, we were able to create a lattice structure using visualization software Material Studio. Such sophisticated structure is found in rhombohedral perovskite system with space group with R3c (#161) and lattice parameter of [Formula: see text], bond angle of [Formula: see text], while treating the exchange–correlation potential with the local density approximations (LDA) method. The calculations were performed to investigate the electronic, optical, elastic and phonon properties.

scholarly journals DFT-based investigation of the electronic structure of a double-stranded AC B-DNA dim

2013 ◽  
Vol 16 ◽  
pp. 117-122
Author(s):  
Emerson Rengifo ◽  
Gustavo Murillo
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Computational Cost ◽  
Semiempirical Method ◽  
Basis Sets ◽  
Functional Theory ◽  
One Dimensional ◽  
Exchange Correlation ◽  
Dna Dodecamer ◽  
Low Computational Cost

Calculations of the electronic structure of a stacked dimmer sequence from the D(GCAAACGTTTGC)2 B-DNA dodecamer resolved in a PDB file 1HQ7 are performed within density functional theory. Seeking to understand the minimum level of theory that yields a reliable description for these systems, the basis sets 6-31g*, 6-31g*+BSSE, 6-311g*, 6-311g**, 6-311++g** along with the B3LYP and PBE0 exchange-correlation functionals were employed. These results are then used to implement a one dimensional model of long stacked systems to obtain a new semiempirical method that can be employed at low computational cost.

Sign in / Sign up

Export Citation Format

Share Document