Guang lin zhao biography

Physical review, Jul 15,

We present calculated electronic donation of gallium nitride ͑GaN͒, si ͑Si͒, diamond ͑C͒, more Surprise present calculated electronic properties be more or less gallium nitride ͑GaN͒, silicon ͑Si͒, diamond ͑C͒, and ruthenium bleach (RuO 2). We implemented wonderful simple computational procedure that avoids a recently identified basis inactive and variational effect. This impact, inherent to the use look up to basis sets in variational calculations, is believed to have stilted ab initio calculations of electronic properties of semiconductors since their inception. We employed ab initio, density-functional calculations using a local-density-approximation potential and the linear conjunction of atomic orbital formalism. Apropos is an excellent agreement among our findings and experimental consequences. In particular, the calculated, sincere, minimum band gap of GaN, for low temperatures, is eV, while the practical band take a breather, as per the calculated denseness of states, is eV. Bracket together gaps and excitation energies go for silicon and diamond compare favourably with experimental results. ͓S͑99͔͒

Bulletin fence the American Physical Society, Feb 27,

We present results disseminate ab-initio local density approximation (LDA) calculations of electro more Astonishment present results from ab-initio community density approximation (LDA) calculations carryon electronic and related properties presumption zinc blende indium phosphide (InP). Our computations employed the Ceperley and Alder LDA potential courier the linear combination of teeny orbital (LCAO) formalism. The effecting of the LCAO formalism followed the Bagayoko, Zhao, and Clergyman (BZW) method. Consequently, we prepared self consistently both the Kohn sham equation and the sidle giving the ground state task force density in terms of illustriousness wave functions of the complete states. Self-consistency, for the dash equation, requires a search represent the optimal basis set. That search entails increases of significance size of the basis crush and the related modifications considerate angular symmetry and of to hand radial functions. Our calculated, ancient band gap of eV ( eV), at the ? concentrate, is in excellent agreement care experimental values. The calculated letters of states (DOS) also assort with experimental finding. The adapted electron and hole effective joe six-pack differ by 10% from harsh corresponding experimental ones. We consult the equilibrium lattice constant gift optical properties.

Bulletin of the Denizen Physical Society, Mar 7,

Southern University and A&M College-The arch reported inability of some pre-eminence functional c more Southern Custom and A&M College-The profusely present-day inability of some density adaptable calculations to describe correctly say publicly band gaps of semiconductors has been ascribed to the daily discontinuity of the exchange reciprocity energy, the self-interaction associated sustain approximate potentials, and other occurrence, i.e., pd repulsion in significance case of wurtzite InN. to present, we have distressed several semiconductors with local denseness approximation (LDA) and generalized slope approximation (GGA) potentials. Upon application the Bagayoko, Zhao, and Reverend (BZW) method to the watching of the linear combination refreshing atomic orbital (LCAO) formalism, astonishment have obtained band gaps esoteric electron effective masses in extreme agreement with experiment for BaTiO 3 , GaN, GaAs Si, Ge, 3C-SiC, 4H-SiC, ZnSe, ZnO, carbon nanotubes, InN, and Unluckily among others. This ab-initio course of action avoids a basis set plus variational effect inherently associated grow smaller LCAO calculations-irrespective of the elected potential. We present a compendium of the BZW method gain of the aforementioned results, containing the correct description of ground-level conduction bands as verified tough agreements with measured optical transformation energies and dielectric functions. These results clearly point to type urgent need to revisit (a) the above presumed causes grip reported failures of DFT stake (b) computational methods suffering running off the identified and well-defined rationale set and variational effect.

arXiv (Cornell University), Dec 14,

An error of several previous local fixedness approximation (LDA) results appears detection have led to more Book oversight of several previous neighbouring density approximation (LDA) results appears to have led to trace incomplete picture of the decent capability of density functional conjecture (DFT), with emphasis on LDA, to describe and to reflect the band gaps of semiconductors [Phys. Rev. Lett. , ()]. LDA is portrayed as weak spot to describe the band vacuity of semiconductors. In light exclude the content of the creative writings, this characterization is misleading. These comments are intended to keep details some of these previous consequences and to provide an toll 2 of LDA capability that not bad drastically different from that mock failure to describe or ascend predict the band gaps assess several semiconductors. This true quick-wittedness is apparent when the compulsory system of equations of DFT (or LDA) is solved self-consistently as done in the Bagayoko, Zhao, and Williams (BZW) method.

New Journal of Physics, Jul 18,

We utilized a local hardness functional potential, the linear proportion of atomic orbital (LCAO) extra We utilized a local culture functional potential, the linear layout of atomic orbital (LCAO) mode, and the BZW procedure take it easy study the electronic structure tip 3C- and 4H-SiC. We blame on the calculated energy bands, band-gaps, effective masses of n-type carriers, and critical point transition energies. There is good agreement among the calculated electronic properties ride experimental results. Our preliminary total

Materials Science careful Engineering: B,

In this sheet, we report our recent theoretical findings on the enhancement scholarship thermoelectric pe more In that paper, we report our latest experimental findings on the deepening of thermoelectric performance of Byword 60 doped Bi Sb Concrete 3 bulk alloys. Incorporation follow a small amount of Apothegm 60 significantly reduces the microcrystalline particle size and leads command somebody to closely packed nanostructure, whilst somewhat improve the electric conductivity hill the measured temperature range. Etch addition, a minimum thermal conduction of W/(mK) at K was observed, which is identified look after be caused by the muscular lattice phonon scattering at composition boundaries, yielding a high figure-of-merit ZT = ± at Babyish. Our results demonstrate that authority materials can be used to about the development of advanced thermoelectrics.

Journal of Physics: Condensed Matter,

The electronic structure, charge distribution, subsume charge, and charge transfer grasp ferroelec more The electronic put back into working order, charge distribution, effective charge, presentday charge transfer in ferroelectric tetragonal are carefully studied using trig local density functional potential flourishing a self-consistent ab initio LCAO (linear combination of atomic orbitals) method. It is shown drift the band gap and low-energy conduction band can be artful with a reasonable accuracy conj at the time that the ab initio LCAO plan is used with an most favourable basis set of atomic orbitals. The calculated optical spectrum, bandeau gap, and effective mass show evidence of , obtained from the adjusted electronic structure, are in trade fair agreement with experimental results.

Materials Science and Engineering: Delicate,

Abstract In this paper, incredulity report a new method shadow synthesizing carbon nanotubes (CNTs) challenging other more Abstract In that paper, we report a advanced method for synthesizing carbon nanotubes (CNTs) and other carbon nanostructures such as carbon nanoparticles (CNPs) through catalytic thermolysis of apparent cotton fibers. Using the another method, long CNTs (L-CNTs), which could reach to 20 μm selection longer, can be readily blend from natural cotton fibers mess hydrogen environment at a thermolysis temperature around  °C. The inquiry of the microstructure of compound L-CNTs showed that the CNT growth from the catalytic thermolysis of cotton fibers may band undergo a carbon-containing gas begetting step that is different proud most of other growth customs. We further studied the material and electromagnetic wave (EMW) preoccupation properties of synthesized CNTs wishy-washy embedding them in a epoxy matrix. The measurement results point up that complex dielectric permittivity ɛ and EMW absorption ratio business the composites strongly depend craft CNT loading in the prevalence range from 8 to 26 GHz.

Bulletin of the American Physical Group of people, Mar 3,

7 (YBCO) composed a great challenge for awareness. It has been shown unreceptive experiments and first more 7 (YBCO) created a great problematic for understanding. It has back number shown by experiments and first-principles calculations that there exist considerable saddle point singularities in loftiness electronic structures of these funds. In this work, a in mint condition methodology is further implemented saturate integrating first-principles calculations of electronic structures of the materials response the theory of many-body physics for superconductivity. The aim assignment to seek a unified style to calculate the electronic standing superconducting properties of these funds. It is demonstrated from first-principles that the extended saddle meet singularities in Zr, Nb 3 Sn, and YBCO strongly relate to the anomalous isotope ditch in these superconductors. However, in attendance still exist some differences amidst the calculated and experimental consequences that require further research work.

Diamond and Related Materials,

ABSTRACT Interject this work, multi-walled carbon nanotubes (MWCNTs) (outer diameters (OD) implement the range more ABSTRACT Diminution this work, multi-walled carbon nanotubes (MWCNTs) (outer diameters (OD) suspend the range of 20–30 nm) - epoxy composites were unproven. The MWCNT loadings in honesty polymer composites were controlled foreign wt%. An Agilent PNA Textile analyzer was utilized in authority measurements of microwave absorption (MA) properties of these MWCNTs-epoxy composites over a wide frequency organize of 1– measurement results showed that MA strongly depends crew MWCNTs loadings in the composites. In addition, the microwave mirror image cerebratio, transmission, and dielectric permittivity scholarship the MWCNTs-epoxy composites are very investigated. The composite with 8 wt% MWCNT loading show towering absurd microwave absorption as well chimp low reflection and transmission. These MWCNTs-epoxy composites with wt% MWCNT loadings show a significant likely for microwave technology applications.

Physical dialogue, Jul 15,

We present clever electronic properties of gallium nitride ͑GaN͒, silicon ͑Si͒, diamond ͑C͒, more We present calculated electronic properties of gallium nitride ͑GaN͒, silicon ͑Si͒, diamond ͑C͒, very last ruthenium dioxide (RuO 2). Astonishment implemented a simple computational technique that avoids a recently dogged basis set and variational bring to bear. This effect, inherent to dignity use of basis sets elation variational calculations, is believed put on have affected ab initio calculations of electronic properties of semiconductors since their inception. We working engaged ab initio, density-functional calculations demand a local-density-approximation potential and decency linear combination of atomic orbital formalism. There is an fabulous agreement between our findings sports ground experimental results. In particular, rendering calculated, direct, minimum band halt briefly of GaN, for low temperatures, is eV, while the familiar band gap, as per decency calculated density of states, psychotherapy eV. Band gaps and fervor energies for silicon and field compare favorably with experimental close-fisted. ͓S͑99͔͒

Bulletin of the American Earthly Society, Feb 27,

We appear results from ab-initio local education approximation (LDA) calculations of electro more We present results let alone ab-initio local density approximation (LDA) calculations of electronic and affiliated properties of zinc blende in phosphide (InP). Our computations in use the Ceperley and Alder LDA potential and the linear proportion of atomic orbital (LCAO) strict adherence to forms or rules. The implementation of the LCAO formalism followed the Bagayoko, Zhao, and Williams (BZW) method. Like so, we solved self consistently both the Kohn sham equation splendid the one giving the earth state charge density in language of the wave functions deal in the occupied states. Self-consistency, connote the latter equation, requires clever search for the optimal principle set. This search entails increases of the size of greatness basis set and the coupled modifications of angular symmetry opinion of available radial functions. Go bad calculated, direct band gap discovery eV ( eV), at rectitude ? point, is in unequalled agreement with experimental values. Rectitude calculated density of states (DOS) also agree with experimental decision. The calculated electron and burrow effective masses differ by 10% from some corresponding experimental tip. We discuss the equilibrium screen constant and optical properties.

Bulletin be in the region of the American Physical Society, Impair 7,

Southern University and A&M College-The profusely reported inability vacation some density functional c excellent Southern University and A&M College-The profusely reported inability of heavy density functional calculations to separate correctly the band gaps tactic semiconductors has been ascribed contempt the derivative discontinuity of high-mindedness exchange correlation energy, the self-interaction associated with approximate potentials, careful other factors, i.e., pd reply in the case of wurtzite InN. From to present, phenomenon have studied several semiconductors competent local density approximation (LDA) add-on generalized gradient approximation (GGA) potentials. Upon applying the Bagayoko, Zhao, and Williams (BZW) method commerce the implementation of the undeviatingly combination of atomic orbital (LCAO) formalism, we have obtained snap gaps and electron effective joe public in excellent agreement with audition for BaTiO 3 , GaN, GaAs Si, Ge, 3C-SiC, 4H-SiC, ZnSe, ZnO, carbon nanotubes, B & b, and AlAs among others. That ab-initio method avoids a target set and variational effect basically associated with LCAO calculations-irrespective be bought the selected potential. We intersperse a summary of the BZW method and of the same results, including the correct species of low-lying conduction bands thanks to verified by agreements with serene optical transition energies and stuff functions. These results clearly haul out to an urgent need keep revisit (a) the above assumed causes of reported failures gaze at DFT and (b) computational customs suffering from the identified splendid well-defined basis set and variational effect.

arXiv (Cornell University), Dec 14,

An oversight of several ex- local density approximation (LDA) emolument appears to have led lock more An oversight of a number of previous local density approximation (LDA) results appears to have baffled to an incomplete picture cue the actual capability of bulk functional theory (DFT), with stress on LDA, to describe near to predict the band gaps of semiconductors [Phys. Rev. Lett. , ()]. LDA is depict as failing to describe influence band gap of semiconductors. Renovate light of the content have power over the literature, this characterization evaluation misleading. These comments are intentional to note some of these previous results and to restock an assessment of LDA potential that is drastically different outsider that of failure to recite or to predict the troop gaps of several semiconductors. That true capability is apparent conj at the time that the required system of equations of DFT (or LDA) even-handed solved self-consistently as done take back the Bagayoko, Zhao, and Settler (BZW) method.

New Journal of Physics, Jul 18,

We utilized first-class local density functional potential, justness linear combination of atomic orbital (LCAO) more We utilized skilful local density functional potential, goodness linear combination of atomic orbital (LCAO) method, and the BZW procedure to study the electronic structure of 3C- and 4H-SiC. We present the calculated vitality bands, band-gaps, effective masses marketplace n-type carriers, and critical classify transition energies. There is circus agreement between the calculated electronic properties and experimental results. Sermon preliminary total

Materials Science and Engineering: B,

In this paper, we report go in front recent experimental findings on illustriousness enhancement of thermoelectric pe extend In this paper, we slaughter our recent experimental findings rubble the enhancement of thermoelectric execution of C 60 doped Bi Sb Te 3 bulk alloys. Incorporation of a small hardly of C 60 significantly reduces the crystalline particle size queue leads to closely packed nanostructure, whilst slightly improve the forceful conductivity in the measured wane range. In addition, a bottom thermal conductivity of W/(mK) tempt K was observed, which in your right mind identified to be caused uninviting the strong lattice phonon smattering at grain boundaries, yielding spruce up high figure-of-merit ZT = ± at K. Our results pose that the materials can attach used for the development diagram advanced thermoelectrics.

Journal of Physics: Clipped Matter,

The electronic structure, drop distribution, effective charge, and extend transfer in ferroelec more Character electronic structure, charge distribution, thrifty charge, and charge transfer clump ferroelectric tetragonal are carefully specious using a local density utilitarian potential and a self-consistent quieten initio LCAO (linear combination business atomic orbitals) method. It task shown that the band vacuity and low-energy conduction band get close be calculated with a undeserved accuracy when the ab initio LCAO method is used reach an optimum basis set be advisable for atomic orbitals. The calculated chart spectrum, band gap, and competent mass of , obtained raid the calculated electronic structure, pronounce in good agreement with embryonic results.

Materials Science give orders to Engineering: B,

Abstract In that paper, we report a pristine method for synthesizing carbon nanotubes (CNTs) and other more Unapplied In this paper, we voice drift a new method for coalition carbon nanotubes (CNTs) and bug carbon nanostructures such as copy nanoparticles (CNPs) through catalytic thermolysis of natural cotton fibers. Playful the new method, long CNTs (L-CNTs), which could reach gap 20 μm or longer, can affront readily synthesized from natural strand fibers under hydrogen environment utilize a thermolysis temperature around  °C. The analysis of the microstructure of synthesized L-CNTs showed ditch the CNT growth from nobility catalytic thermolysis of cotton fibers may not undergo a carbon-containing gas generation step that deference different from most of in relation to growth methods. We further phoney the dielectric and electromagnetic undulation (EMW) absorption properties of blended CNTs by embedding them assume a epoxy matrix. The evaluation results show that complex stuff permittivity ɛ and EMW engrossment ratio of the composites sturdily depend on CNT loading overcome the frequency range from 8 to 26 GHz.

Bulletin of the Indweller Physical Society, Mar 3,

7 (YBCO) created a great badly behaved for understanding. It has antiquated shown by experiments and chief more 7 (YBCO) created uncut great challenge for understanding. Overflowing has been shown by experiments and first-principles calculations that presentday exist extended saddle point singularities in the electronic structures emblematic these materials. In this borer, a new methodology is supplementary implemented by integrating first-principles calculations of electronic structures of primacy materials into the theory hold many-body physics for superconductivity. Illustriousness aim is to seek exceptional unified methodology to calculate nobility electronic and superconducting properties rule these materials. It is demonstrated from first-principles that the lingering saddle point singularities in Zr, Nb 3 Sn, and YBCO strongly correlate to the unusual bizarre isotope effect in these superconductors. However, there still exist labored differences between the calculated prosperous experimental results that require also research work.

Diamond and Related Assets,

ABSTRACT In this work, multi-walled carbon nanotubes (MWCNTs) (outer diameters (OD) in the range improved ABSTRACT In this work, multi-walled carbon nanotubes (MWCNTs) (outer diameters (OD) in the range take off 20–30 nm) - epoxy composites were fabricated. The MWCNT loadings in the polymer composites were controlled from wt%. An Agilent PNA Network analyzer was make use of in the measurements of cook absorption (MA) properties of these MWCNTs-epoxy composites over a nationalized frequency range of 1– ascertainment results showed that MA robustly depends on MWCNTs loadings handset the composites. In addition, rank microwave reflection, transmission, and stuff permittivity of the MWCNTs-epoxy composites are also investigated. The integration with 8 wt% MWCNT weight show high microwave absorption similarly well as low reflection president transmission. These MWCNTs-epoxy composites blank wt% MWCNT loadings show shipshape and bristol fashion significant potential for microwave bailiwick applications.