Electronic Structure Studies of Diamond/Metal Interfaces

1990 ◽  
Vol 193 ◽  
Author(s):  
Steven C. Erwin ◽  
Warren C. Pickett
Keyword(s):  
Total Energy ◽  
Barrier Height ◽  
Valence Band Maximum ◽  
Microscopic Level ◽  
Relative Positioning ◽  
Lattice Match ◽  
Minimum Total Energy ◽  
Tentative Explanation ◽  
Metal Interfaces ◽  
Total Energy Minimum

ABSTRACTWe have begun to investigate theoretically the electronic properties of several ideal epitaxial interfaces of diamond with Ni and Cu, both of which enjoy a close lattice match. Of particular interest is the mechanism responsible for formation of the Schottky barrier, which is not yet fully understood at the microscopic level. We find that both the barrier height and the chemical bonding at the interface are strongly dependent on interface orientation (i.e., the relative positioning of the two surfaces). For orientations near the minimum total energy geometry, the calculated Fermi level is apparently pinned around 1.7 and 2.1 eV for the (111) and (001) interfaces, respectively, relative to the valence band maximum. For orientations not near the total energy minimum, the calculated barrier height is zero. A tentative explanation for this difference is proposed.

The application of an optimization technique to the development of universal basis sets

1992 ◽  
Vol 70 (2) ◽  
pp. 580-588 ◽  
Author(s):  
R. Custodio ◽  
J. D. Goddard ◽  
M. Giordan ◽  
N. H. Morgon
Keyword(s):  
Total Energy ◽  
Energy Criterion ◽  
Basis Set ◽  
Basis Sets ◽  
Weight Functions ◽  
Statistical Criterion ◽  
Minimum Total Energy ◽  
Discretization Technique ◽  
Universal Bases ◽  
Molecular Calculations

The Simplex method was used to define atomic and universal meshes using the integral discretization technique for the Griffin–Hill–Wheeler-Hartree–Fock equations. This technique represents a basis set as an exponential set of the form:[Formula: see text]For atoms, the minimum total energy criterion was employed. For the universal basis, three different procedures were tested: (a) defining the universal basis using information on the isolated atoms, (b) determining the universal Ω0(k) through atomic calculations and reoptimizing the ΔΩ(k) for different symmetries employing simultaneously a single atomic calculation as a reference point, and (c) optimizing the universal mesh using a statistical criterion such as the squares of the deviations of the total energy. The meshes obtained by the minimum total energy criterion or the squares of deviations of the total energy for the universal basis are accurate for the total energy but the weight functions are deficient in the valence region. Shifting the optimized Ω0(k) to [Formula: see text], fixing [Formula: see text], and reoptimizing ΔΩ(k) for each symmetry species produces a better description of weight functions at the expense of a less accurate total energy. In general, no significant statistical difference was observed for the various universal bases generated by procedures (a) and (b) or by (c) provided the shift correction was made to the latter. Application of these bases to diatomic molecules (N2, CO, P2, CS) showed that the universal bases are as accurate as those optimized for atomic systems. If the bases are transferred from atoms to molecules, the shift corrections to the weight functions of the atoms are not useful in molecular calculations. The almost equivalent molecular properties and the good total energies show that the best basis for molecular calculations is that optimized by procedure (c). Keywords: universal basis sets, integral discretization technique.

scholarly journals Improving the energy method for calculating beams with a narrow rectangular section on the side buckling

2020 ◽  
Vol 164 ◽  
pp. 02033
Author(s):  
Serdar Yazyev ◽  
Anastasia Lapina ◽  
Ivan Zotov ◽  
Anton Chepurnenko ◽  
Irina Doronkina
Keyword(s):  
Analytical Solution ◽  
Total Energy ◽  
Energy Method ◽  
Strain Energy ◽  
Vertical Displacement ◽  
Center Of Gravity ◽  
Rectangular Section ◽  
Minimum Total Energy ◽  
The Stability ◽  
External Forces

We propose an improved version of the energy method in calculating rectangular beams for the stability of a flat bending shape. The essence of this variant of the method is to use the principle of the minimum total energy instead of the condition for the equality of the potential strain energy and the work of external forces. This version of the method makes it easy to obtain a numerical-analytical solution for any number of members of series. The solution of the problem for a pivotally supported beam is presented taking into account the vertical displacement of the load relative to the center of gravity.

scholarly journals First principles study of Schottky barriers at Ga2O3(100)/metal interfaces

RSC Advances ◽  
2020 ◽  
Vol 10 (25) ◽  
pp. 14746-14752
Author(s):  
Ran Xu ◽  
Na Lin ◽  
Zhitai Jia ◽  
Yueyang Liu ◽  
Haoyuan Wang ◽  
...  
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
First Principles ◽  
High Performance ◽  
Schottky Barrier Height ◽  
Electronic Devices ◽  
Schottky Barriers ◽  
First Principles Study ◽  
Metal Interfaces ◽  
Semiconductor Contact

A low Schottky barrier height (SBH) of metal–semiconductor contact is essential for achieving high performance electronic devices.

The Effects of Foot Trajectory on the Power Required to Swing a Mechanical Leg

1989 ◽  
Vol 203 (6) ◽  
pp. 419-428 ◽  
Author(s):  
D McCloy
Keyword(s):  
Total Energy ◽  
Degree Of Freedom ◽  
Knee Joints ◽  
Optimum Conditions ◽  
Dynamic Effects ◽  
Minimum Total Energy ◽  
Two Degree Of Freedom ◽  
Foot Trajectory

The paper examines a two-degree-of-freedom serial-operated mechanical leg, driven by rotary actuators at hip and knee joints. When determining dynamic effects, three foot trajectories are compared: (a) ballistic, in which the foot is literally thrown from the end of the step to its start, (b) rectangular and (c) smoothed rectangular. In each case the conditions for minimum total energy are determined. In addition, when the trajectory is a smoothed rectangle, energies and powers for each actuator are calculated, and optimum conditions determined.

scholarly journals Application of new method in quantum-mechanical calculations of the structural properties and the formation energy of the ordered Mu - phase in the Fe - Mo system

2021 ◽  
Vol 2052 (1) ◽  
pp. 012048
Author(s):  
A L Udovsky ◽  
D A Vasilyev
Keyword(s):  
Total Energy ◽  
Formation Energy ◽  
Plane Waves ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Minimum Total Energy ◽  
A New Technique ◽  
Formation Energies ◽  
Crystal Lattice Parameters ◽  
Account Relaxation

Abstract A new technique of finding the minimum total energy, calculated by quantum mechanical calculations, for hexagonal Mu- (μ-) phases of stoichiometric compositions taking into account relaxation, as well as optimized crystal lattice parameters for different compositions in the Fe-Mo system, has been applied. The convergence of the total energy is investigated as a function of the number of plane waves (k) in the range 2000 ÷ 105. Differences in the structural energies between bcc, C14 Laves and μ- phases of pure components, as well as the formation energies of μ- phases of stoichiometric compositions Fe9Mo4, Fe7Mo6 and Fe6Mo7 are calculated.

scholarly journals Energy Justification of the Number of Tractors for Agricultural Operations

2021 ◽  
Vol 37 ◽  
pp. 00136
Author(s):  
Camill A. Khafizov ◽  
Ramil N. Khafizov ◽  
Azat A. Nurmiev ◽  
Ilgiz G. Galiev
Keyword(s):  
Mathematical Model ◽  
Total Energy ◽  
System Analysis ◽  
Optimal Number ◽  
Computational Experiments ◽  
Energy Costs ◽  
Total Energy Consumption ◽  
Agricultural Producers ◽  
Main Research ◽  
Minimum Total Energy

The relevance of the problem under study is due to the need to substantiate the sufficient number of tractors used for various technological operations, depending on the volume of works performed, and taking into account their influence on the crop yield. The purpose is to develop the mathematical model of machine and tractor units used in technological operations by formalizing the vague concept of optimal agrotechnical timing of technological operations and calculating the optimal number of tractors to perform works by the total energy costs. The main research method is mathematical modeling of operations performed by machine-tractor units based on the system analysis and computational experiments and using the energy mathematical model. The article describes a criterion for optimizing the tractor parameters, dependences of the energy mathematical model of the unit. The results of computational experiments showed that for each operation there is an optimal number of tractors and tractor units minimizing the minimum total energy costs. Calculations were carried out when treating 1000 hectares with various tractors. It was revealed that the total energy consumption differs by 2 or more times. The required number of tractors depends on their main parameters, propeller parameters and other factors. It was revealed that with an increase in the volume of works, the required optimal number of tractors increases. The method for substantiating the required optimal number of tractors in technological operations will improve operations of tractors used by large agricultural producers, reduce the total energy costs for cultivating up to 12–16 thousand MJ/ha.

Trimethylammoniodiformylmethylide: Structure and charge distribution

1980 ◽  
Vol 45 (1) ◽  
pp. 80-91 ◽  
Author(s):  
Vladimír Král ◽  
Zdeněk Arnold
Keyword(s):  
Dipole Moment ◽  
Total Energy ◽  
Ab Initio ◽  
Charge Distribution ◽  
Quantum Chemical ◽  
Energy Minimum ◽  
Chemical Methods ◽  
Quantum Chemical Methods ◽  
Total Energy Minimum

Geometric arrangement of trimethylammoniodiformylmethylide (I) and charge distribution in this compound were calculated by quantum chemical methods (EHT, CNDO/2, INDO, PCILO, MINDO/2, ab initio). Total energy minimum was found for the arrangement If. The experimentally found dipole moment agrees very well with that calculated for this conformation.

scholarly journals The External Electric Field-Induced Tunability of the Schottky Barrier Height in Graphene/AlN Interface: A Study by First-Principles

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1794
Author(s):  
Xuefei Liu ◽  
Zhaocai Zhang ◽  
Bing Lv ◽  
Zhao Ding ◽  
Zijiang Luo
Keyword(s):  
Electric Field ◽  
Schottky Barrier ◽  
External Electric Field ◽  
Barrier Height ◽  
Density Functional ◽  
Schottky Barrier Height ◽  
Schottky Contact ◽  
Valence Band Maximum ◽  
Charge Analysis ◽  
P Type

Graphene-based van der Waals (vdW) heterojunction plays an important role in next-generation optoelectronics, nanoelectronics, and spintronics devices. The tunability of the Schottky barrier height (SBH) is beneficial for improving device performance, especially for the contact resistance. Herein, we investigated the electronic structure and interfacial characteristics of the graphene/AlN interface based on density functional theory. The results show that the intrinsic electronic properties of graphene changed slightly after contact. In contrast, the valence band maximum of AlN changed significantly due to the hybridization of Cp and Np orbital electrons. The Bader charge analysis showed that the electrons would transfer from AlN to graphene, implying that graphene would induce acceptor states. Additionally, the Schottky contact nature can be effectively tuned by the external electric field, and it will be tuned from the p-type into n-type once the electric field is larger than about 0.5 V/Å. Furthermore, the optical absorption of graphene/AlN is enhanced after contact. Our findings imply that the SBH is controllable, which is highly desirable in nano-electronic devices.

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