Theoretical studies of structural stability at high pressure

1995 ◽  
Vol 73 (5-6) ◽  
pp. 253-257 ◽  
Author(s):  
John S. Tse ◽  
Dennis D. Klug
Keyword(s):  
Molecular Dynamics ◽  
High Pressure ◽  
First Principles ◽  
High Pressures ◽  
Structural Phase ◽  
Md Simulations ◽  
Quantum Molecular Dynamics ◽  
First Principles Calculations ◽  
Quantum Mechanical Effects ◽  
Structural Memory

Theoretical methods are indispensible for the study of matter at high pressure. In the last decade the development of accurate intermolecular potentials and the methodologies in classical molecular dynamics (MD) simulations have greatly facililated the applications of these methods to the study of structural phase transformamtions of solids at high pressures. More recently, it has been possible to incorporate quantum mechanical effects into MD calculations. This method eliminates a great deal of empiricism. These first principles calculations have not only reproduced the experimental results for phase transformations but also provided detailed mechanisms and in some cases predicted new structures that may be found at high pressures. The success of MD calculations is illustrated through a review of our studies of pressure-induced amorphization and phase transitions in SiO2 and TiO2, and the structural memory effect in several materials. Current applications using quantum molecular dynamics on ice are discussed.

Theoretical aspects in structural distortion and the electronic properties of lithium peroxide under high pressure

2018 ◽  
Vol 20 (14) ◽  
pp. 9488-9497 ◽  
Author(s):  
Pornmongkol Jimlim ◽  
Komsilp Kotmool ◽  
Udomsilp Pinsook ◽  
Suttichai Assabumrungrat ◽  
Rajeev Ahuja ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Electronic Properties ◽  
Structural Phase Transition ◽  
First Principles ◽  
Structural Phase ◽  
Structural Distortion ◽  
First Principles Calculations ◽  
Lithium Peroxide

The structural phase transition and electronic properties of Li2O2 under pressures up to 500 GPa have been investigated using first-principles calculations.

Structural Phase Transition and Electronic Properties of MgCe under High Pressure from First-Principles Calculations

2014 ◽  
Vol 577 ◽  
pp. 102-107
Author(s):  
Qiu Xiang Liu ◽  
De Ping Lu ◽  
Rui Jun Zhang ◽  
Lei Lu ◽  
Shi Fang Xie
Keyword(s):  
Phase Transition ◽  
Ground State ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
High Pressures ◽  
Local Density ◽  
Structural Phase ◽  
First Principles Calculations ◽  
Functional Theory

The structural stability of MgCe under high pressures has been investigated by using the first-principles plane-wave pseudopotential density functional theory within the local density approximation (LDA). The obtained results predict that MgCe in the Ba structure is predicted to be the most stable structure corresponding to the ground state, because of lowest total energy. MgCe undergoes a pressure-induced phase transition from the Ba structure to B32 structure at 36 GPa. And no further transition is found up to 120 GPa. In addition, the electronic structures of four structures of MgCe are also calculated and discussed.

Phase transition and electronic properties of SbI3: First-principles calculations

2017 ◽  
Vol 31 (18) ◽  
pp. 1750200 ◽  
Author(s):  
Xiao-Xiao Sun ◽  
Cong Li ◽  
Qing-Yu Hou ◽  
Yue Zhang
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Electronic Properties ◽  
First Principles ◽  
Structural Phase ◽  
Relative Volume ◽  
First Principles Calculations ◽  
Volume Collapse ◽  
Pseudopotential Calculations ◽  
Indirect Band Gap

We have performed the first-principles pseudopotential calculations to investigate the structural phase transition and electronic properties of SbI3 considering several possible phases as a function of pressure from 0 GPa to 100 GPa. Our calculations show that this material undertakes a structural transformation from the R-3 phase to high-pressure [Formula: see text] phase at about 6.5 GPa with a relative volume collapse of 4.3%. We also have investigated the elastic properties and energy band structure of SbI3 under hydrostatic pressure. The calculation suggests that the R-3 phase is a semiconductor with an indirect band gap of about 2.16 eV at 0 Gpa. Under the influence of pressure, we have found that high-pressure [Formula: see text] phase has transformed to metal at about 55 GPa.

First-Principles Investigations on Electronic, Elastic and Thermodynamic Properties of VN under High Pressure

2012 ◽  
Vol 550-553 ◽  
pp. 2805-2809 ◽  
Author(s):  
Ai Min Hao ◽  
Xiao Cui Yang ◽  
Li Xin Zhang ◽  
Qi Zhou Zhang
Keyword(s):  
High Pressure ◽  
Thermodynamic Properties ◽  
First Principles ◽  
Density Functional ◽  
Structural Phase ◽  
Basis Set ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Elevated Pressures ◽  
Cscl Type

An investigation on electronic, elastic and thermodynamic properties of VN under high pressure has been conducted using first-principles calculations based on density functional theory (DFT) with the plane wave basis set as implemented in the CASTEP code. At elevated pressures VN is predicted to undergo a structural phase transition from the relatively open NaCl-type structure into the denser CsCl-type atomic arrangement. The predicted transition pressure is 189 GPa. The elastic constants, Debye temperature as a function of pressure and temperature of VN are presented.

First-Principles Calculations of Electronic and Structural Properties of LaN under High Pressure

2013 ◽  
Vol 331 ◽  
pp. 563-566 ◽  
Author(s):  
Xiao Cui Yang ◽  
Fang Liu ◽  
Xiang Yi Luo ◽  
Hong Yu Lin ◽  
Jun Ping Xiao
Keyword(s):  
High Pressure ◽  
First Principles ◽  
Density Functional ◽  
Structural Phase ◽  
Type Structure ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Elevated Pressures ◽  
Cscl Type ◽  
Valence Bands

An investigation on the electronic structures and structural stability of LaN under high pressure has been conducted using first-principles calculations based on density functional theory (DFT). At elevated pressures LaN is predicted to undergo a structural phase transition from NaCl-type to CsCl-type structure. The predicted transition pressure is 65 GPa. The result of elastic constants indicates that the NaCl-type structure is mechanically a stable structure and the CsCl-type strcture is not mechanically a stable one. The calculated band structure of LaN is semimetallic.the conduction and valence bands.

First-Principles Calculations and Molecular Dynamics Simulations on Effect of Hydrogen Impurity in Lead Titanate Films

2016 ◽  
Author(s):  
Lin Zhu ◽  
Jeong Ho You ◽  
Jinghong Chen
Keyword(s):  
Molecular Dynamics ◽  
First Principles ◽  
Hysteresis Loops ◽  
Md Simulations ◽  
Energy Difference ◽  
Effective Hamiltonian ◽  
First Principles Calculations ◽  
Hydrogen Impurity ◽  
Penalty Term ◽  
Energy Penalty

Properties of ferroelectric films are highly influenced by inevitable defects, such as hydrogen impurity. This study is focused on theoretical and numerical studies to probe effects of hydrogen contamination on ferroelectric stability in PbTiO3 (PTO) films using the first-principles effective Hamiltonian. First-principles calculations are performed to determine the possible position, formation energy, and mobility of hydrogen impurity atom, and the calculated results are used as inputs to molecular dynamics (MD) simulations in a large system. The hydrogen atom is able to move along the polarization with small energy barriers. The energy difference between a hydrogen contaminated PTO and a pure PTO is considered as an energy penalty term induced by hydrogen contamination and has been added to the effective Hamiltonian. Then, the MD effective Hamiltonian with the energy penalty is employed in MD simulations to investigate the effects of hydrogen contamination on the ferroelectric responses of PTO films with various thicknesses and temperatures. The hysteresis loops are presented and analyzed for PTO films with various concentrations of hydrogen impurities and thicknesses. Hydrogen contamination reduces the remnant polarization, especially for thin films. As the concentration of hydrogen impurities increases, the critical thickness increases. By analyzing the vertical cross section snapshots, it has been found that the hydrogen impurity atoms near interfaces affect the polarization throughout the entire PTO films.

Atomic simulations of GB sliding in pure and segregated bicrystals

2013 ◽  
Vol 1515 ◽  
Author(s):  
Motohiro Yuasa ◽  
Yasumasa Chino ◽  
Mamoru Mabuchi
Keyword(s):  
Molecular Dynamics ◽  
Electronic Structure ◽  
Grain Boundary ◽  
Charge Density ◽  
First Principles ◽  
Deformation Mode ◽  
Md Simulations ◽  
Bond Critical Point ◽  
First Principles Calculations ◽  
Atomic Simulations

ABSTRACTGrain boundary (GB) sliding is an important deformation mode in polycrystals, and it has been extensively investigated, for example, there are many studies on influences of the atomic geometry in the GB region. However, it is important to investigate GB sliding from the electronic structure of GB for deeper understandings of the sliding mechanisms. In the present work, we investigated the GBs sliding in pure and segregated bicrystals with classical molecular dynamics (MD) simulations and first-principles calculations. It is accepted that the sliding rate is affected by the GB energy. However, there was no correlation between the sliding rate and the GB energy in either the pure or the segregated bicrystals. First-principles calculations revealed that the sliding rate calculated by the MD simulations increases with decreasing minimum charge density at the bond critical point in the GB. This held in both the pure and segregated bicrystals. It seems that the sliding rate depends on atomic movement at the minimum charge density sites.

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