scholarly journals Ab Initio High-Pressure Study of Semiconductor-Metal Phase Transition of the Chalcogenide Compound KPSe6

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
P. O. Jomo ◽  
C. O. Otieno ◽  
P. W. O. Nyawere
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Ab Initio ◽  
Density Functional ◽  
Basis Sets ◽  
Metal Phase ◽  
Generalized Gradient ◽  
Energy Calculations ◽  
Metal Phase Transition ◽  
Chalcogenide Compound

We report the results of pressure-induced semiconductor-metal phase transition of the semiconducting chalcogenide compound KPSe6 under high pressure using the ab initio methods. The ground-state energy calculations were performed within density functional theory and the generalized gradient approximation using the pseudopotential method with plane-wave basis sets. The projector augmented-wave (PAW) pseudopotentials were used in our calculation. The optimized lattice parameters were found from total energy calculations as 13 Bohr, 1.6 Bohr, and 1.8 Bohr for cell dimensions one, two, and three, respectively, which are in good agreement with experimental calculations. At zero pressure, the material portrayed a semiconducting property with a direct bandgap of ≈1.7 eV. As we subjected the material to pressure, the band gap was observed to reduce until it disappeared. The phase transition from the semiconductor to metal was found to occur at ∼45 GPa, implying that the material underwent metallization as pressure was increased further.

Pressure induced semiconductor–metal phase transition in GaAs: experimental and theoretical approaches

RSC Advances ◽  
2016 ◽  
Vol 6 (12) ◽  
pp. 10144-10149 ◽  
Author(s):  
Jia Wang ◽  
Baojia Wu ◽  
Guozhao Zhang ◽  
Lianhua Tian ◽  
Guangrui Gu ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
First Principles ◽  
Metal Phase ◽  
First Principles Calculations ◽  
Electrical Measurements ◽  
Theoretical Approaches ◽  
Metal Phase Transition

GaAs undergoes a semiconductor–metal transition, which was investigated by in situ electrical measurements and first-principles calculations under a high pressure.

Semiconductor-metal phase transition in LaBi under high pressure

2015 ◽  
Vol 57 (8) ◽  
pp. 1639-1641 ◽  
Author(s):  
N. N. Stepanov ◽  
N. V. Morozova ◽  
A. E. Kar’kin ◽  
I. V. Korobeinikov ◽  
A. V. Golubkov ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Metal Phase ◽  
Metal Phase Transition

FIRST-PRINCIPLES STUDY OF THE STRUCTURAL, ELECTRONIC AND OPTICAL PROPERTIES OF MgSiO3 AT HIGH PRESSURE

2009 ◽  
Vol 20 (07) ◽  
pp. 1093-1101 ◽  
Author(s):  
YANLING LI ◽  
ZHI ZENG
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Plane Waves ◽  
Generalized Gradient ◽  
Equation Of States ◽  
Phase Transition Pressure ◽  
Pnma Phase

The high-pressure behavior of perovskite ( MgSiO 3) is studied based on density functional simulations within generalized gradient approximation (GGA). All calculations are performed by using the linear augmented plane waves plus local orbital (LAPW+lo) method to solve the scalar-relativistic Kohn-Sham equations. The static calculations predict a perovskite (pnma phase) — post-perovskite (Cmcm phase) transition occurring at 86 gigapascals (GPa). The similar bulk modulus values, differing only 3 GPa, are given by using three kinds of equation of states. The electronic structure and optical properties of MgSiO 3 at phase transition pressure are also discussed.

On the nature of homo- and hetero-dinuclear metal–metal quadruple bonds — Analysis of the bonding situation and benchmarking DFT against wave function methods

2010 ◽  
Vol 88 (11) ◽  
pp. 1079-1093 ◽  
Author(s):  
Nozomi Takagi ◽  
Andreas Krapp ◽  
Gernot Frenking
Keyword(s):  
Ab Initio ◽  
Dissociation Energy ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Bond Distance ◽  
Basis Sets ◽  
Energy Decomposition Analysis ◽  
Generalized Gradient ◽  
Metal Bond ◽  
Metal Metal

Homo- and hetero-dimetallic (d–d)8 analogues of the formally quadruply bonded [Re2Cl8]2– system with the general formula [MM′Cl8]x (M, M′ = Tc, Re, Ru, Os, Rh, Ir and x = –2, –1, 0, +1, +2) have been calculated with the density functional theory (DFT) functionals SVWN, BLYP, BP86, PBE, OLYP, OPBE, HCTH, B3LYP, O3LYP, X3LYP, BH&HLYP, TPSS, VSXC, TPPSh, and ab initio methods (CASPT2, CCSD(T)) using basis sets of triple-ζ quality. The performance of the functionals for the description of the metal–metal bond distance and the bond dissociation energy as well as the singlet–triplet gap was evaluated with respect to ab initio data at the CASPT2 level. Generally, the generalized gradient approximation (GGA) functionals, BLYP, BP86, and PBE, show good performance in the description of the metal–metal bond distance and for the dissociation energy. Hybrid functionals are not to be used for compounds of the type discussed here as they lead to increasingly too short and too weak bonds with the amount of exact exchange included. All functionals underestimate the singlet–triplet gap, with the GGA functionals BLYP, BP86, PBE being the closest to the CASPT2 values. The bonding situations of the [MM′Cl8]x compounds were analyzed at the DFT level (BP86) using the natural bond orbital (NBO) method and the energy decomposition analysis. The M–M bond in homodimetallic compounds, [MMCl8]x, becomes weaker from group 7 to group 8 to group 9 metals and the bond is weaker for 4d metal systems than for 5d transition metal compounds. The M–M bonds have approximately 50% covalent and 50% electrostatic character and the covalent contribution is dominated by the π orbitals, whereas the δ orbitals do not contribute significantly to the covalent bonding. Heterodimetallic systems, [MM′Cl8]x, have significantly stronger metal–metal bonds than the homodimetallic compounds. This comes from weaker Pauli repulsion and stronger electrostatic attraction. The most stable heterodimetallic bonds are observed for 5d–5d metal pairs.

Kinetics and Atomic Mechanisms of Structural Phase Transformations in Photoexcited Monolayer TMDCs

MRS Advances ◽  
2018 ◽  
Vol 3 (6-7) ◽  
pp. 345-350
Author(s):  
Aravind Krishnamoorthy ◽  
Lindsay Bassman ◽  
Rajiv K. Kalia ◽  
Aiichiro Nakano ◽  
Fuyuki Shimojo ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Density Functional ◽  
Structural Phase ◽  
Transition Metal Dichalcogenides ◽  
Optical Excitation ◽  
Metal Phase ◽  
Rapid Phase ◽  
Metal Dichalcogenides ◽  
Metal Phase Transition

ABSTRACTRapid transitions between semiconducting and metallic phases of transition-metal dichalcogenides are of interest for 2D electronics applications. Theoretical investigations have been limited to using thermal energy, lattice strain and charge doping to induce the phase transition, but have not identified mechanisms for rapid phase transition. Here, we use density functional theory to show how optical excitation leads to the formation of a low-energy intermediate crystal structure along the semiconductor-metal phase transition pathway. This metastable crystal structure results in significantly reduced barriers for the semiconducting-metal phase transition pathway leading to rapid transition in optically excited crystals.

Electronic Structure Of (AgSb)xPbn-2xTen

2003 ◽  
Vol 793 ◽  
Author(s):  
Daniel I Bilc ◽  
S.D. Mahanti ◽  
M.G. Kanatzidis
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Density Functional ◽  
Full Potential ◽  
Generalized Gradient ◽  
Two Component System ◽  
Functional Theory ◽  
Covalent Interaction ◽  
Salt Structure ◽  
Linearized Augmented Plane Wave

ABSTRACTComplex quaternary chalcogenides (AgSb)xPbn-2xTen (0<x<n/2) are thought to be narrow band-gap semiconductors which are very good candidates for room and high temperature thermoelectric applications. These systems form in the rock-salt structure similar to the well known two component system PbTe (x=0). In these systems Ag and Sb occupy Pb sites randomly although there is some evidence of short-range order. To gain insights into the electronic structure of these compounds, we have performed electronic structure calculations in AgSbTe2 (x=n/2). These calculations were carried out within ab initio density functional theory (DFT) using full potential linearized augmented plane wave (LAPW) method. The generalized gradient approximation (GGA) was used to treat the exchange and correlation potential. Spinorbit interaction (SOI) was incorporated using a second variational procedure. Since it is difficult to treat disorder in ab initio calculations, we have used several ordered structures for AgSbTe2. All these structures show semimetallic behavior with a pseudogap near the Fermi energy. Te and Sb p orbitals, which are close in energy, hybridize rather strongly indicating a covalent interaction between Te and Sb atoms.

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