Ab Initio Study of Structural Phase Transition and Electronic Properties in Samarium (Sm) Compounds

2016 ◽  
Vol 1141 ◽  
pp. 184-189
Author(s):  
Yeshvir Singh Panwar ◽  
Mahendra Aynyas ◽  
Jagdeesh Pataiya ◽  
Sankar P. Sanyal
Keyword(s):  
Phase Transition ◽  
Bulk Modulus ◽  
Structural Phase Transition ◽  
Local Density ◽  
Structural Phase ◽  
Tight Binding ◽  
Energy Band Diagram ◽  
Lattice Parameter ◽  
Type B ◽  
Lmto Method

The electronic structure and high pressure structural phase transition of SmTe and SmPo have been studied by using tight binding linear muffin-tin-orbital (TB-LMTO) method within the local density approximation (LDA). The total energy as a function of volume is obtained and it is found that these compounds are stable in NaCl-type (B1-phase) structure and transform to CsCl-type (B2-type) structure. The transition pressure of SmTe and SmPo are found to be 6.6 GPa and 8.6 GPa respectively. We have also calculated lattice parameter (a0), bulk modulus (B0), band structure (BS) and density of states (DOS). From energy band diagram, we observed that these compounds exhibit weakly metallic behaviour. The calculated values of lattice parameter and bulk modulus agree well with the available data.

Structural and Electronic Properties of Thulium Compounds

2016 ◽  
Vol 28 ◽  
pp. 59-64
Author(s):  
Yeshvir Singh Panwar ◽  
Mahendra Aynyas ◽  
Jagdeesh Pataiya ◽  
Sankar P. Sanyal
Keyword(s):  
Bulk Modulus ◽  
Local Density ◽  
Structural Phase ◽  
Tight Binding ◽  
Energy Band Diagram ◽  
Lattice Parameter ◽  
Band Diagram ◽  
Cscl Type ◽  
Structural And Electronic Properties ◽  
Lmto Method

The tight binding linear muffin-tin-orbital (TB-LMTO) method within the local density approximation (LDA) is used to study the electronic structure and high pressure behaviour of thulium compounds TmX (X= P, As, S, and Se). We also predict a structural phase transition from NaCl to CsCl-type structure. The transition pressures were found to be 40.0, 31.0, 58.0 and 49.0 GPa, for TmP, TmAs, TmS and TmSe respectively. Apart from this, the lattice parameter (a0), bulk modulus (B0), band structure and density of states are calculated. From energy band diagram, it is observed that these compounds exhibit weak metallic character. The calculated values of lattice parameters and bulk modulus are of reasonable agreement with available data.

Pressure Induced Structural and Electronic Properties of Thulium Nitride

2014 ◽  
Vol 1047 ◽  
pp. 147-150
Author(s):  
Yeshvir Singh Panwar ◽  
Mahendra Aynyas ◽  
M.K. Tejraj ◽  
S.P. Sanyal
Keyword(s):  
Phase Transition ◽  
Bulk Modulus ◽  
Electronic Properties ◽  
Structural Phase Transition ◽  
Phase Structure ◽  
Local Density ◽  
Ambient Pressure ◽  
Structural Phase ◽  
Lattice Parameter ◽  
Type B

We report ab initio calculations of pressure induced structural phase transition and electronic properties of thulium nitride (TmN). The total energy as a function of volume is obtained by using the self-consistent tight binding linear muffin-tin-orbital (TB-LMTO) method within the local density approximation (LDA). It is found that TmN is stable in NaCl – type structure under ambient pressure. We predict a structural phase transition from NaCl-type (B1-phase) structure to CsCl-type (B2-phase) structure of this compound at a high pressure of 68 GPa. We also calculate the lattice parameter (a0), bulk modulus (B0), band structure and density of states. From energy band diagram it is observed that TmN exhibit metallic behaviour. The calculated values of equilibrium lattice parameter and bulk modulus are in general good agreement with available experimental data.

Ab Initio Study of Pressure Induced Structural, Magnetic and Electronic Properties in Plutonium Pnictides

2014 ◽  
Vol 1047 ◽  
pp. 11-17 ◽  
Author(s):  
Chandrabhan Makode ◽  
Jagdeesh Pataiya ◽  
M. Aynyas ◽  
Sankar P. Sanyal
Keyword(s):  
Bulk Modulus ◽  
Total Energy ◽  
Electronic Properties ◽  
Ambient Pressure ◽  
Structural Phase ◽  
Tight Binding ◽  
Energy Band Diagram ◽  
Lattice Parameter ◽  
Local Spin Density Approximation ◽  
Type B

We have investigated the pressure induced structural and electronic properties of plutonium pnictides (PuY, Y= P, As, Sb). The total energy as a function of volume is obtained by means of self-consistent tight binding linear muffin-in-orbital (TB-LMTO) method within the local spin density approximation (LSDA). From present study with the help of total energy calculations (spin polarized) it is found that PuP, PuAs and PuSb are stable in NaCl – type structure under ambient pressure. The structural stability of PuP, PuAs and PuSb changes under the application of pressure. We predict a structural phase transition from NaCl-type (B1-phase) to CsCl-type (B2-phase) structure for these Pu-pnictides in the pressure range of 20.8 – 42.0 GPa. We also calculate the lattice parameter, bulk modulus, band structure and density of states. From energy band diagram it is observed that all the three compounds exhibit metallic behaviour. The calculated equilibrium lattice parameters and bulk modulus are in good agreement with available experimental data.

scholarly journals First Principles Study of Electronic Structure and Magnetic Properties of TMH (TM = Cr, Mn, Fe, Co)

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
S. Kanagaprabha ◽  
R. Rajeswarapalanichamy ◽  
K. Iyakutti
Keyword(s):  
Phase Transition ◽  
Magnetic Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Local Density ◽  
Hexagonal Phase ◽  
Structural Phase ◽  
Tight Binding ◽  
Transition Metal Hydrides ◽  
Lmto Method

First principles calculations are performed using a tight-binding linear muffin-tin orbital (TB-LMTO) method with local density approximation (LDA) and atomic sphere approximation (ASA) to understand the electronic properties of transition metal hydrides (TMH) (TM = Cr, Mn, Fe, Co). The structural property, electronic structure, and magnetic properties are investigated. A pressure induced structural phase transition from cubic to hexagonal phase is predicted at the pressures of 50 GPa for CrH and 23 GPa for CoH. Also, magnetic phase transition is observed in FeH and CoH at the pressures of 10 GPa and 180 GPa, respectively.

First Principle Calculations of Pressure Induced Structural and Electronic Properties in Americium Monochalcogenides

2014 ◽  
Vol 1047 ◽  
pp. 35-40 ◽  
Author(s):  
Jagdeesh Pataiya ◽  
Mahendra Aynyas ◽  
Chandrabhan Makode ◽  
Archana Singh ◽  
Sankar P. Sanyal
Keyword(s):  
Bulk Modulus ◽  
Energy Band ◽  
Phase Structure ◽  
Local Density ◽  
Ambient Pressure ◽  
Structural Phase ◽  
Tight Binding ◽  
Theoretical Data ◽  
Lattice Parameters ◽  
Type B

The tight-binding linear muffin-tin orbital (TB-LMTO) with in the local density approximation is used to calculate total energy, lattice parameters, bulk modulus, density of states and energy band structures of americium monochalcogenides at ambient as well as high pressure. It is found that AmX (X=S, Se, Te) compounds are stable in NaCl – type structure under ambient pressure. We predict a structural phase transition from NaCl-type (B1-phase) structure to CsCl-type (B2-phase) structure for these compounds in the pressure range of 26.0 – 15.0 GPa (AmS to AmTe). From energy band diagram it is observed that AmX compounds exhibit metallic behaviour. The calculated ground state properties such as lattice parameters and bulk modulus are in general good agreement with available experimental and theoretical data.

Pressure-induced Structural Phase Transition of Carbon Nanotubes into New Nanostructured Carbon Solids

2009 ◽  
Vol 1204 ◽  
Author(s):  
Masahiro Sakurai ◽  
Susumu Saito
Keyword(s):  
Phase Transition ◽  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Structural Phase Transition ◽  
Density Functional ◽  
Local Density ◽  
Structural Phase ◽  
Tight Binding ◽  
Dynamics Simulation ◽  
Nanotube Bundles

AbstractWe study pressure-induced structural phase transition of carbon nanotubes using the constant-pressure tight-binding molecular-dynamics simulation. The systems studied are nanotube bundles composed of (6,6) armchair nanotube and/or (7,4) chiral nanotube, which are reported to be the nanotubes relatively abundant in experimentally purified sample. We find that the nanotube bundles transforms into a new phase that consist of graphitic ribbons and diamond blocks, “graphitic nanoribbon solid”. It is also found that sp3-rich phases obtained from the armchair nanotubes possess an anisotropic network and have high hardness which is comparable to that of cubic diamond. In the case of the bundles containing chiral nanotubes, on the other hand, amorphous diamond phase is obtained. Based on the local-density approximation in the density-functional theory, we also investigate the energetics and electronic structure of some of new carbon phases obtained in the molecular-dynamics study.

PRESSURE-INDUCED METALLIZATION AND SUPERCONDUCTIVITY IN InP AND InN

2011 ◽  
Vol 25 (04) ◽  
pp. 573-587
Author(s):  
K. IYAKUTTI ◽  
V. REJILA ◽  
M. RAJARAJESWARI ◽  
C. NIRMALA LOUIS ◽  
S. MAHALAKSHMI
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Structural Phase Transition ◽  
Electronic Band Structure ◽  
Indium Nitride ◽  
Structural Phase ◽  
Superconducting Transition ◽  
Electronic Band ◽  
Zinc Blende ◽  
Lmto Method

The electronic band structure, structural phase transition, metallization and superconducting transition of cubic zinc blende-type indium phosphide ( InP ) and indium nitride ( InN ), under pressure, are studied using TB-LMTO method. These indium compounds become metals and superconductors under high pressure but before that they undergo structural phase transition from ZnS to NaCl structure. The ground-state properties and band gap values are compared with the experimental and previous theoretical results. From our analysis, it is found that the metallization pressure increases with increase of lattice constant. The superconducting transition temperatures (Tc) of InP and InN are obtained as a function of pressure for both the ZnS and NaCl structures and these compounds are identified as pressure-induced superconductors. When pressure is increased Tc increases in both the normal ( ZnS ) and high pressure ( NaCl ) structures. The dependence of Tc on electron–phonon mass enhancement factor λ shows that InP and InN are electron–phonon mediated superconductors. The non-occurrence of metallization, phase transition and onset of superconductivity simultaneously in InP and InN are confirmed.

Ab Initio Study of Pressure-Induced Structural Properties of Uranium Chalcogenides

2014 ◽  
Vol 1047 ◽  
pp. 155-161
Author(s):  
Archana Singh ◽  
Mahendra Aynyas ◽  
S.P. Sanyal
Keyword(s):  
Phase Transition ◽  
Structural Phase Transition ◽  
Phase Structure ◽  
Structural Phase ◽  
Tight Binding ◽  
First Principles Calculation ◽  
Orbital Method ◽  
Cscl Type ◽  
Spin Polarized ◽  
Total Energies

We report a first principles calculation of pressure-induced structural phase transition properties of uranium chalcogenides (UX; X=S, Se and Te). The total energies as a function of volume are obtained by means of self-consistent tight binding linear muffin orbital method (TB-LMTO) by performing spin and non-spin polarized calculations to determine the magnetic and structural stabilities. From the present study, we predict a magnetic phase transition from ferromagnetic (FM) to non-magnetic (NM) state around 67.7 and 10.2 GPa for US and USe, respectively. The pressure-induced magnetic transitions are found second-order in nature. We have also predicted structural phase transition from FM-NaCl-type (B1phase) structure to NM-CsCl-type (B2phase) structure at around 77.5, 23.5 for US and USe, respectively, while UTe undergoes from FM-B1to FM-B2phase around 12.0 GPa.

Structural Phase Stability of ThSb Under Pressure

1994 ◽  
Vol 364 ◽  
Author(s):  
B. Palanivel ◽  
G. Kalpana ◽  
M. Rajagopalan
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Cell Volume ◽  
Structural Transition ◽  
Structural Phase ◽  
Tight Binding ◽  
Lmto Method ◽  
Cscl Structure ◽  
Total Energies ◽  
Good Agreement

AbstractThe electronic structure and high pressure structural phase transition in thorium antimonide have been investigated using the tight binding LMTO method. We have calculated the total energies by reducing the cell volume for NaCl as well as CsCl structures using TBLMTO method. The total energy calculations reveal that ThSb undergoes a structural transition from NaCl to CsCl structure at 78 kbar. The calculated value of equilibrium cell volume and the cell volume at which phase transition occurs are found to have a good agreement with the experimental results.

BAND STRUCTURE, METALLIZATION AND SUPERCONDUCTIVITY OF InP AND InN UNDER HIGH PRESSURE

2012 ◽  
Vol 11 (01) ◽  
pp. 19-33 ◽  
Author(s):  
A. AMAL RAJ ◽  
C. NIRMALA LOUIS ◽  
V. REJILA ◽  
K. IYAKUTTI
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Band Structure ◽  
Structural Phase Transition ◽  
Electronic Band Structure ◽  
Indium Nitride ◽  
Structural Phase ◽  
Superconducting Transition ◽  
Electronic Band ◽  
Lmto Method

The electronic band structure, structural phase transition, metallization and superconducting transition of cubic zinc blende type indium phosphide (InP) and indium nitride (InN), under pressure, are studied using FP-LMTO method. These indium compounds become metals and superconductors under high pressure but before that they undergo structural phase transition from ZnS to NaCl structure. The ground state properties and band gap values are compared with the experimental and previous theoretical results. From our analysis, it is found that the metallization pressure increases with increase of lattice constant. The superconducting transition temperatures (Tc) of InP and InN are obtained as a function of pressure for both the ZnS and NaCl structures and these compounds are identified as pressure induced superconductors. When pressure is increased Tc increases in both the normal ( ZnS ) and high pressure ( NaCl ) structures. The dependence of Tc on electron–phonon mass enhancement factor λ shows that InP and InN are electron–phonon mediated superconductors. The non-occurrence of metallization, phase transition and onset of superconductivity simultaneously in InP and InN is confirmed.

Sign in / Sign up

Export Citation Format

Share Document