Sulfur bonding in cyclic P2S2N4 systems: a density functional comparison of 1,1,5,5-tetramethylbicyclo[3.3.0]-1,5-diphospha-3,7-dithia-2,4,6,8-tetrazocine with the 1,1,3,5,5-pentamethyl-1,5-diphospha-3,7-dithia-2,4,6,8-tetrazocine anion

1994 ◽  
Vol 72 (6) ◽  
pp. 1582-1586 ◽  
Author(s):  
Heiko Jacobsen ◽  
Tom Ziegler ◽  
Tristram Chivers ◽  
Rainer Vollmerhaus
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Bond Strength ◽  
Sulfur Atom ◽  
Density Functional ◽  
Correlation Energy ◽  
Local Density ◽  
Density Approximation ◽  
Functional Theory ◽  
Sulfur Bond

The electronic structure and the bonding of the title compounds have been investigated using density functional theory within the local density approximation, adding nonlocal corrections to exchange and correlation energy. The çross-ring sulfur-sulfur bond energy in 1,1,5,5-tetramethylbicyclo[3.3.0]-1,5-diphospha-3,7-dithia-2,4,6,8-tetrazocine was estimated to be about 133 kJ/mol. The HOMO of the 1,1,3,5,5-pentamethyl-1,5-diphospha-3,7-dithia-2,4,6,8-tetrazocine anion is mainly localized at the site of the unmethylated sulfur atom and is antibonding with respect to the sulfur—carbon bond of the methylated sulfur atom, which has a relatively weak estimated bond strength of 218 kJ/mol.

First-Principles Study on the Electronic Structure of N-Doped Orthorhombic SrHfO3

2011 ◽  
Vol 239-242 ◽  
pp. 1231-1234
Author(s):  
Qi Jun Liu ◽  
Zheng Tang Liu ◽  
Li Ping Feng ◽  
Hao Tian
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Charge Transfer ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Density Approximation ◽  
Functional Theory ◽  
Bonding Properties ◽  
Valence Bands

The electronic properties of N-doped orthorhombic SrHfO3 have been calculated using the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory with the local density approximation. From the calculated band structure and density of states, the bandgap reduction is observed due to the presence of the N-2p states in the top of valence bands, which leads to red-shift. Moreover, in order to clarify the charge transfer and bonding properties of N-doped orthorhombic SrHfO3, we have calculated and analysed the charge density.

TIME-DEPENDENT DENSITY FUNCTIONAL STUDY OF MULTIELECTRON TRANSFER IN Cq+–Na4 COLLISIONS

2010 ◽  
Vol 24 (24) ◽  
pp. 4811-4820
Author(s):  
Y. P. ZHANG ◽  
F. S. ZHANG ◽  
Y. GAO ◽  
H. W. CHANG ◽  
G. Q. XIAO
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Local Density ◽  
Time Dependent ◽  
Functional Study ◽  
Density Approximation ◽  
Functional Theory ◽  
The Difference ◽  
Multielectron Transfer ◽  
Dependent Density

The process of multielectron transfer from a Na 4 cluster induced by highly charged C 6+, C 4+, C 2+ and C + ions is studied using the method of time-dependent density functional theory within the local density approximation combined with the use of pseudopotential. The evolution of dipole moment changes and emitted electrons in Na 4 is obtained and the time-dependent probabilities with various charges are deduced. It is shown that the Na 4 cluster is strongly ionized by C 6+ and that the number of emitted electrons per atom of Na 4 is larger than that of Na 2 under the same condition. One can find that the detailed information of the emitted electrons from Na 4 is different from the same from Na 2, which is possibly related to the difference in structure between the two clusters.

Study of Thermodynamic Properties of Superhard w-BC2N

2013 ◽  
Vol 750-752 ◽  
pp. 1141-1145
Author(s):  
Ai Ling Ding ◽  
Feng Li ◽  
Chun Mei Li ◽  
Jing Ao ◽  
Zhi Qian Chen
Keyword(s):  
Density Functional Theory ◽  
Heat Capacity ◽  
Thermodynamic Properties ◽  
Density Functional ◽  
Local Density ◽  
Density Functional Theory Method ◽  
Debye Model ◽  
Theory Method ◽  
Density Approximation ◽  
Functional Theory

We investigate the thermodynamic properties of superhard w-BC2N by using ab initio plane-wave pseudopotential density functional theory method within local density approximation (LDA). Through the quasi-harmonic Debye model, we investigate the thermodynamic properties of w-BC2N. The variation of the thermal expansion, the heat capacity and the Gruneisen parameter γ with pressure P and temperature T, and many other thermodynamic parameters of w-BC2N are obtained systematically.

First-principles Calculations of Energetic Properties of Vacancies, Mn-atomic Defects in CdTe

2006 ◽  
Vol 959 ◽  
Author(s):  
Ghouti Merad ◽  
Benali Rerbal ◽  
Hafid Aourag ◽  
Joël Cibert
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Density Approximation ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Energetic Properties ◽  
Atomistic Modelling ◽  
Atomic Type

ABSTRACTAn atomistic modelling based on density functional theory within the framework of the local density approximation is used to show the trends in the energetic properties of single and double defects in CdTe semiconductor, without phase transformation. A systematic study of vacancies, Mn substituting Cd atoms in a supercell structure consisting of 16-atoms is presented. The changes of structural properties and lattice parameters due to the addition of Mn-atomic type defects in CdTe matrix are compared, and the number of vacancies is also determined from the total energy calculations.

ELECTRONIC AND DYNAMICAL PROPERTIES OF MgB2 AND RELATED COMPOUNDS

2002 ◽  
Vol 16 (11n12) ◽  
pp. 1563-1569 ◽  
Author(s):  
G. PROFETA ◽  
A. CONTINENZA ◽  
F. BERNARDINI ◽  
G. SATTA ◽  
S. MASSIDDA
Keyword(s):  
Density Functional Theory ◽  
Local Density Approximation ◽  
Density Functional ◽  
Local Density ◽  
Density Approximation ◽  
Superconducting Properties ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Dynamical Properties ◽  
Related Compounds

We report a detailed study of the electronic and dynamical properties of MgB2 , BeB2 and of the AlMgB4 superlattice, within the local density approximation to the density functional theory. On the basis of our results we discuss the superconducting properties of these systems, and point to the high T c in MgB2 as a fortunate combination of events.

THE PROBLEM OF THE BAND GAP IN LDA CALCULATIONS

2007 ◽  
Vol 14 (03) ◽  
pp. 481-487 ◽  
Author(s):  
I. N. YAKOVKIN ◽  
P. A. DOWBEN
Keyword(s):  
Density Functional Theory ◽  
Band Structure ◽  
Band Gap ◽  
Local Density Approximation ◽  
Density Functional ◽  
Local Density ◽  
Fine Tuning ◽  
Density Approximation ◽  
Functional Theory ◽  
Basic Physics

In calculating band structure, the local density approximation and density functional theory are widely popular and do reproduce a lot of the basic physics. Regrettably, without some fine tuning, the local density approximation and density functional theory do not generally get the details of the experimental band structure correct, in particular the band gap in semiconductors and insulators is generally found to be too small when compared with experiment. For experimentalists using commercial packages to calculate the electronic structure of materials, some caution is indicated, as some long-standing problems exist with the local density approximation and density functional theory.

STABILITY ANALYSIS OF SMALL COPPER NANOCLUSTERS

2012 ◽  
Vol 11 (01) ◽  
pp. 1250006
Author(s):  
PRABODH SAHAI SAXENA ◽  
PANKAJ SRIVASTAVA ◽  
ASHWANI Kr. SHRIVASTAVA
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Local Density ◽  
Binding Energies ◽  
Density Approximation ◽  
Copper Nanoclusters ◽  
Functional Theory ◽  
Total Energies ◽  
Homo Lumo ◽  
Atom Bond

We have investigated the lowest-energy structures and electronic properties of the Cu n(n = 2–10) nanoclusters based on density functional theory (DFT) in local density approximation. The total energies, binding energies per atom, bond lengths, HOMO-LUMO gaps and ionization potentials have been calculated. The results are compared well with other theoretical and available experimental results.

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