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We develop a general and unified first-principles theory of piezoelectric and flexoelectric tensor, formulated in such a way that the tensor elements can be computed directly in the context of density-functional calculations, including…

Materials Science · Physics 2013-11-21 Jiawang Hong , David Vanderbilt

This review of quantitative field emitter electrostatics, covering analytical, numerical and fitted-formula approaches, is thought the first of its kind. The review relates chiefly to situations where emitters operate in an electronically…

Mesoscale and Nanoscale Physics · Physics 2023-02-07 Thiago A. de Assis , Fernando F. Dall'Agnol , Richard G. Forbes

A large area field emitter (LAFE) typically consists of several thousands of nanoscale emitting tips. These are difficult to simulate using purely numerical methods based on finite/boundary element or finite difference methods. We show here…

Applied Physics · Physics 2022-07-21 Debabrata Biswas , Rashbihari Rudra , Raghwendra Kumar

We develop an analytical theory of polarization of a vertically aligned array of carbon nanotubes (NTs) in external electric field. Such arrays are commonly utilized in field-emission devices, due to the known electrostatic effect of strong…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 T. A. Sedrakyan , E. G. Mishchenko , M. E. Raikh

Large area field electron emitters, typically consisting of several thousands of nanotips, pose a major challenge since numerical modeling requires enormous computational resources. We propose a hybrid approach where the local electrostatic…

Applied Physics · Physics 2022-01-06 Debabrata Biswas

We propose a dynamical mean field approach for calculating the electronic structure of strongly correlated materials from first principles. The scheme combines the GW method with dynamical mean field theory, which enables one to treat…

Strongly Correlated Electrons · Physics 2009-11-07 S. Biermann , F. Aryasetiawan , A. Georges

Electronic transport properties in armchair shaped edges graphene nanoribbons (AGNRs) doped various impurities have been simulated by the non-equilibrium Green's function approach combined with the first principle calculation based on the…

Mesoscale and Nanoscale Physics · Physics 2015-06-05 Hiroyoshi Tsuyuki , Shoichi Sakamoto , Mitsuyoshi Tomiya

The thorough treatment of electron-lattice interactions from first principles is one of the main goals in condensed matter physics. While the commonly applied adiabatic Born-Oppenheimer approximation is sufficient for describing many…

We present details of our effective computational methods based on the real-space finite-difference formalism to elucidate electronic and magnetic properties of the two-dimensional (2D) materials within the framework of the density…

Mesoscale and Nanoscale Physics · Physics 2016-10-05 Yoshiyuki Egami , Shigeru Tsukamoto , Tomoya Ono

We overview nonequilibrium Green function combined with density functional theory (NEGF-DFT) modeling of independent electron and phonon transport in nanojunctions with applications focused on a new class of thermoelectric devices where a…

Mesoscale and Nanoscale Physics · Physics 2012-04-19 Branislav K. Nikolic , Kamal K. Saha , Troels Markussen , Kristian S. Thygesen

Electronic transport properties of carbon nanotubes are studied theoretically in the presence of external electric field E(t) by using the Boltzmann's transport with constant relaxation time. An analytical expression for the current…

Mesoscale and Nanoscale Physics · Physics 2015-02-18 S. S. Abukari , S. Y. Mensah , N. G. Mensah , M. Rabiu , K. W. Adu , A. Twum

We put forward a first-principle NonEquilibrium Green's Function (NEGF) approach to calculate the transient photoabsorption spectrum of optically thin samples. The method can deal with pump fields of arbitrary strength, frequency and…

Atomic Physics · Physics 2015-09-30 E. Perfetto , A. -M. Uimonen , R. van Leeuwen , G. Stefanucci

We review different computational methods for the calculation of photoelectron spectra and angular distributions of atoms and molecules when excited by laser pulses using time-dependent density-functional theory (TDDFT) that are suitable…

Chemical Physics · Physics 2017-03-28 Philipp Wopperer , Umberto De Giovannini , Angel Rubio

In the present work, the application of the method of underwater arc discharge of graphite electrodes for obtaining several carbon nanostructures is described. The analysis of the obtained products by Transmission Electron Microscopy (TEM),…

A computational method is developed whereby the reflectivity of low-energy electrons from a surface can be obtained from a first-principles solution of the electronic structure of the system. The method is applied to multilayer graphene.…

Mesoscale and Nanoscale Physics · Physics 2014-01-21 R. M. Feenstra , M. Widom

We present a thermodynamical investigation of the alpha-gamma transition of Ce using first principles calculation based on the combination of Density Functional Theory with Dynamical Mean Field Theory. First, the scheme allows for an…

Strongly Correlated Electrons · Physics 2014-06-04 Jordan Bieder , Bernard Amadon

Grain boundaries play a major role for electron transport in graphene sheets grown by chemical vapor deposition. Here we investigate the electronic structure and transport properties of idealized graphene grain boundaries (GBs) in…

Mesoscale and Nanoscale Physics · Physics 2024-03-19 Aleksander Bach Lorentzen , Fei Gao , Peter Bøggild , Antti-Pekka Jauho , Mads Brandbyge

ultiwalled carbon nanotubes, prepared by both electric arc discharge and chemical vapor deposition methods, show a strong visible light emission in photoluminescence experiments. All the samples employed in the experiments exhibit nearly…

Materials Science · Physics 2007-05-23 H. X. Han , G. H. Li , W. K. Ge , Z. P. Wang , Z. Y. Xu , S. S. Xie , B. H. Chang , L. F. Sun , B. S. Wang , G. Xu , Z. B. Su

Hydrogen embrittlement in metals is strongly governed by hydrogen diffusion and trapping, yet predicting these effects in polycrystalline systems remains challenging. This work introduces a multiscale modeling framework that links atomistic…

Materials Science · Physics 2026-01-12 Bhanuj Jain , Alaa Olleak , Junyan He , Adarsh Chaurasia , Davide Di Stefano

A first-principle model is proposed to study the electrostatic properties of a double-gated silicon slab of nano scale in the framework of density functional theory. The applied gate voltage is approximated as a variation of the…

Materials Science · Physics 2008-12-02 Li-Na Zhao , Xue-Feng Wang , Zhen-Hua Yao , Zhu-Feng Hou , Marcus Yee , Xing Zhou , Shi-Huan Lin , Teck-Seng Lee