Electronic Structure, Pressure Dependence and Optical Properties of FeS2

1997 ◽  
Vol 491 ◽  
Author(s):  
D. Nguyen-Manh ◽  
D. G. Pettifor ◽  
H. M. Sithole ◽  
P. E. Ngoepe ◽  
C. Arcangeli ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Tight Binding ◽  
Structure Study ◽  
Dramatic Improvement ◽  
Full Potential ◽  
Iron Pyrite ◽  
Energy Band Gap ◽  
Equilibrium Lattice Constant ◽  
Observed Behaviour ◽  
Efficient Packing

ABSTRACTA revisited electronic structure study of iron pyrite, FeS2, has been performed using a new Tight-Binding Linear Muffin-Tin Orbital (TB-LMTO) technique in which the radii of overlapping MT spheres are determined from a full potential construction. The interstitial spheres were chosen to provide an efficient packing of space while ensuring that the overlap between the spheres remain small. We have found that this treatment of interstitial spheres results in a dramatic improvement in the description of the electronic structure and the binding energy curves for FeS2 in comparison with a previous LMTO calculation. In particular, the energy band gap, the equilibrium lattice constant and the bulk modulus are all in much better agreement with experimental observations. Moreover, the calculated equation of state is in excellent accord with recent measured P- V data up to pressures of 15GPa with overall deviations of less than 10%. The predicted reflectivity spectrum of FeS2 as a function of pressure gives the observed behaviour of the optical edge. The bonding behaviour the orthorhombic marcasite phase of FeS2 is also discussed within this new TB-LMTO formalism.

Electronic Structure and Atomic Configuration of Extended Defects in Metals by First-Principles and Semiempirical TB-LMTO Methods

1997 ◽  
Vol 491 ◽  
Author(s):  
M. Šob ◽  
I. Turek ◽  
V. Vitek
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Magnetic Moments ◽  
Tight Binding ◽  
Local Environment ◽  
Ground State Structure ◽  
Full Potential ◽  
Extended Defects ◽  
Semiempirical Approach ◽  
Sphere Approximation

ABSTRACTWe present two tight-binding linear muffin-tin orbitals (TB-LMTO) techniques for electronic structure calculations of extended defects (such as grain boundaries, interphase interfaces, surface layers etc.) in metals. The first is based on the first-principles self-consistent surface Green's function approach within the atomic-sphere approximation (ASA) utilizing two-dimensional periodicity in the layers parallel to the interface. In the second approach the Hamiltonian is constructed within the TB-LMTO-ASA as well, but semiempirical terms are employed to characterize the repulsive part of the interaction and the effect of electrons in interstitial space. While the adjustable parameters have only been fitted to the properties of ideal ground state structure, the semiempirical approach describes correctly the structural energy differences, phonon frequencies etc. Two examples are presented: the electronic structure of the Σ = 5(210)/[001] tilt grain boundary in tungsten is determined and the sensitivity of 4d magnetic moments in thin films to local environment is discussed. A comparison of the semiempirical TB-LMTO-ASA with the first-principles full-potential LMTO results is performed along the trigonal deformation path connecting the bcc, simple cubic and fee structures and the applicability of the semiempirical approach for simulating atomic structure of extended defects is assessed.

scholarly journals Electronic Structure Study of Divanadium Complexes with Rigid Covalent Coordination: Potential Molecular Qubits with Slow Spin Relaxation

2021 ◽  
Author(s):  
Stephen Sproules
Keyword(s):  
Electronic Structure ◽  
Spin Relaxation ◽  
Ground State ◽  
Electronic Structures ◽  
Structure Study ◽  
Ligand Shell

The electronic structures of homovalent [V2(μ-S2)2(R2dtc)4] (R = Et, iBu) and mixed-valent [V2(μ-S2)2(R2dtc)4]+ are reported here. The soft-donor, eight-coordinate ligand shell combined with the fully delocalised ground state provides a...

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