Complex band structure with non-orthogonal basis set: analytical properties and implementation in the SIESTA code

Analytical Properties ◽

Overlap Matrix ◽

Orthogonal Case ◽

Periodic Calculations

Abstract The complex band structure, although not directly observable, determines many properties of a material where the periodicity is broken, such at surfaces, interfaces and defects. Furthermore, its knowledge helps in the interpretation of electronic transport calculations and in the study of topological materials. Here we extend the transfer matrix method, often used to compute the complex bands, to electronic structures constructed using an atomic non-orthogonal basis set. We demonstrate that when the overlap matrix is not the identity, the non-orthogonal case, spurious features appear in the analytic continuation of the band structure to the complex plane. The properties of these are studied both numerically and analytically and discussed in the context of existing literature. Finally, a numerical implementation to extract the complex band structure from periodic calculations carried out with the density functional theory code SIESTA is presented. This is constructed as a simple post-processing tool, and it is therefore amenable to high-throughput studies of insulators and semiconductors.

Electronic structure of the thermoelectric materials PbTe and AgPb18SbTe20 from first-principles calculations

Journal of Materials Research ◽

10.1557/jmr.2010.0145 ◽

2010 ◽

Vol 25 (6) ◽

pp. 1030-1036 ◽

Cited By ~ 4

Author(s):

Pengxian Lu ◽

Zigang Shen ◽

Xing Hu

Keyword(s):

Band Structure ◽

Thermoelectric Properties ◽

First Principles ◽

Electronic Structures ◽

Density Functional ◽

Partial Density ◽

Functional Theory ◽

Scanning Transmission ◽

Linearized Augmented Plane Wave

To investigate the effects of substituting Ag and Sb for Pb on the thermoelectric properties of PbTe, the electronic structures of PbTe and AgPb18SbTe20 were calculated by using the linearized augmented plane wave based on the density-functional theory of the first principles. By comparing the differences in the band structure, the partial density of states (PDOS), the scanning transmission microscope, and the electron density difference for PbTe and AgPb18SbTe20, we explained the reason from the aspect of electronic structures why the thermoelectric properties of AgPb18SbTe20 could be improved significantly. Our results suggest that the excellent thermoelectric properties of AgPb18SbTe20 should be attributed in part to the narrowing of its band gap, band structure anisotropy, the much extrema and large DOS near Fermi energy, as well as the large effective mass of electrons. Moreover, the complex bonding behaviors for which the strong bonds and the weak bonds are coexisted, and the electrovalence and covalence of Pb–Te bond are mixed should also play an important role in the enhancement of the thermoelectric properties of the AgPb18SbTe20.

Calculation of the Band Structure for GaAs and ZnTe Nanoparticles from the Density Functional Theory Based on LDA, GGA and HSE06

Eurasian Journal of Science and Engineering ◽

10.23918/eajse.v4i3sip31 ◽

2019 ◽

Vol 4 (3) ◽

Keyword(s):

Band Structure ◽

Density Functional ◽

Functional Theory ◽

The Density Functional Theory

A Density Functional Theory Study of the Isomerization of Substituted 2and#39;-hydroxychalcones to the Corresponding Flavanones

Journal of the chemical society of pakistan ◽

10.52568/000549/jcsp/43.01.2021 ◽

2021 ◽

Vol 43 (1) ◽

pp. 25-25

Author(s):

Said Abdelqadar Said Said Abdelqadar Said ◽

Omar A Shareef and Abdulkhalik S Alkazzaz Omar A Shareef and Abdulkhalik S Alkazzaz

Keyword(s):

Density Functional ◽

Ring Closure ◽

Basis Set ◽

Functional Theory ◽

Rate Determining Step ◽

Electronic And Structural Properties ◽

Maximum Hardness Principle

The transformation of 2and#39;-hydroxychalcones to their corresponding flavanones was studied theoretically by the use of the density functional theory (DFT) with B3-LYP/ 6-311G basis set to get important information about the role of both of electronic and structural properties in this process. The obtained energies were found to be in agreement with our previous results that obtained from HPLC studies. The estimated hardness, polarizability, and electrophilicity profiles were found to obey the maximum hardness principle (MHP), minimum polarizability principle (MPP), and the minimum electrophilicity principle (MEP) respectively. Flavanone ring closure was found to be the rate-determining step.

FIRST-PRINCIPLES STUDIES ON THE ELECTRONIC STRUCTURE OF LuPd2Si2

International Journal of Modern Physics B ◽

10.1142/s0217979209054466 ◽

2009 ◽

Vol 23 (32) ◽

pp. 5929-5934 ◽

Cited By ~ 1

Author(s):

T. JEONG

Keyword(s):

Band Structure ◽

First Principles ◽

Density Functional ◽

Electronic Band Structure ◽

Local Density ◽

Spin Orbit Coupling ◽

Electronic Band ◽

Functional Theory ◽

Structure Scheme

The electronic band structure of LuPd 2 Si 2 was studied based on the density functional theory within local density approximation and fully relativistic schemes. The Lu 4f states are completely filled and have flat bands around -5.0 eV. The fully relativistic band structure scheme shows that spin–orbit coupling splits the 4f states into two manifolds, the 4f7/2 and the 4f5/2 multiplet.

Analysis of vibratinal spectra of 8-hydroxyquinoline and its 5,7-dichloro, 5,7-dibromo, 5,7-diiodo and 5,7-dinitro derivatives based on density functional theory calculations

Open Chemistry ◽

10.2478/s11532-006-0061-x ◽

2007 ◽

Vol 5 (1) ◽

pp. 201-220 ◽

Cited By ~ 12

Author(s):

Khaled Bahgat ◽

Abdel Ragheb

Keyword(s):

Dft Calculations ◽

Density Functional ◽

Density Functional Theory Calculations ◽

Basis Set ◽

Normal Coordinate ◽

Functional Theory ◽

Vibrational Bands ◽

Good Agreement

AbstractThe geometry, frequency and intensity of the vibrational bands of 8-hydroxyquinoline and its 5,7-dichloro, 5,7-dibromo, 5,7-diiodo and 5,7-dinitro derivatives were obtained by the density functional theory (DFT) calculations with Becke3-Lee-Parr (B3LYP) functional and 6-31G* basis set. The effects of chloride, bromide, iodide and nitro substituent on the vibrational frequencies of 8-hydroxyquinoline have been investigated. The assignments have been proposed with aid of the results of normal coordinate analysis. The observed and calculated spectra are found to be in good agreement.

The difference in stability between 5′R and 5′S diastereomers of 5′,8-cyclopurine-2′-deoxynucleosides. DFT study in gaseous and aqueous phase

Open Chemistry ◽

10.2478/s11532-009-0104-1 ◽

2010 ◽

Vol 8 (1) ◽

pp. 134-141 ◽

Cited By ~ 1

Author(s):

Boleslaw Karwowski

Keyword(s):

Density Functional ◽

Bond Cleavage ◽

Basis Set ◽

Small Range ◽

Functional Theory ◽

Formic Acid Hydrolysis ◽

The Difference ◽

The Stability ◽

First Time

AbstractOxidatively generated damage to DNA frequently appears in the human genome as an effect of aerobic metabolism or as the result of exposure to exogenous oxidizing agents. Due to these facts it has been decided to calculate the stability of 5′,8-cyclo-2′-deoxyadenosine/guanosine (cdA, cdG) in their 5′R and 5′S diastereomeric forms. For all points of quantum mechanics studies presented, the density functional theory (DFT) with B3LYP parameters on 6-311++G** basis set level was used. The calculations showed a significant negative enthalpy for glycosidic bond cleavage reaction for cationic forms and slightly negative for neutral ones. The preliminary study of the discussed process has shown the nature of stepwise nucleophilic substitution DN*AD type mechanism. Surprisingly, the different values in free energy, between short-lived oxacarbenium ion intermediates, have been found to lie over a relatively small range, around 1 and 2.8 kcal mol−1. For anions, the decomposition enthalpies were found as positive in aqueous phases. These theoretical results are supported by the formic acid hydrolysis experiments of both diastereomers of cdA, for the first time. (5′S)cdA exhibited higher stability than (5′R)cdA.

Structural characterization of kaempferol: a spectroscopic and computational study

Macedonian Journal of Chemistry and Chemical Engineering ◽

10.20450/mjcce.2019.1333 ◽

2019 ◽

Vol 38 (1) ◽

pp. 49 ◽

Cited By ~ 2

Author(s):

Dejan Milenković ◽

Jasmina M Dimitrić Marković ◽

Dušan Dimić ◽

Svetlana Jeremić ◽

Dragan Amić ◽

...

Keyword(s):

Density Functional ◽

Computational Study ◽

Chemical Shifts ◽

Absolute Error ◽

Nbo Analysis ◽

Basis Set ◽

Functional Theory ◽

Spectroscopic Characteristics

Calculations based on the density functional theory, with the B3LYP functional and the 6-311++G(d,p) basis set, were performed with the aim of confirming the molecular structure and spectroscopic characteristics of kaempferol, a naturally occurring flavonoid molecule. The electronic structure of kaempferol was examined using NBO analysis. The assigning of the experimentally obtained IR and Raman spectra was performed after the best-fit-based comparison with theoretical spectra. The 13C and 1H NMR experimental spectra were related to the theoretically obtained values of the chemical shifts determined by the GIAO method. The correlation coefficient and the average absolute error values proved B3LYP-D3 to be an adequate method in describing the NMR parameters of kaempferol. Molecular docking analysis was carried out in order to identify the potency of inhibition of the title molecule against human procalcitonin. The inhibition activity was obtained for 10 conformations of ligand inside the protein.

Substantial Variations in the Optical Absorption and Reflectivity of Graphene When the Concentrations of Vacancies and Doping with Fluorine, Nitrogen, and Oxygen Change

International Journal of Molecular Sciences ◽

10.3390/ijms22136832 ◽

2021 ◽

Vol 22 (13) ◽

pp. 6832

Author(s):

Ali Fransuani Jiménez-González ◽

Juan Manuel Ramírez-de-Arellano ◽

Luis Fernando Magaña

Keyword(s):

Optical Absorption ◽

Band Structure ◽

Numerical Simulations ◽

Ab Initio ◽

Density Functional ◽

Functional Theory ◽

Density Values

We performed ab initio numerical simulations with the density functional theory to investigate the variations in the band structure, optical absorption, and the reflectivity of vacancy-graphene doped with nitrogen, oxygen, and fluorine for different densities. We considered the density values 0.78%, 1.02%, 1.39%, 2.00%, 3.12%, 5.55%, and 12.5% for the vacancies and doping. In the infrared and visible ranges for all cases, vacancies included, there is a substantial increment in the absorption and reflectivity concerning graphene. The most significant changes are for fluorine and oxygen at a concentration of 12.5%.

A Density Functional Theory Study of the Isomerization of Substituted 2and#39;-hydroxychalcones to the Corresponding Flavanones

Journal of the chemical society of pakistan ◽

10.52568/000369 ◽

2021 ◽

Vol 43 (1) ◽

pp. 25-25

Author(s):

Said Abdelqadar Said Said Abdelqadar Said ◽

Omar A Shareef and Abdulkhalik S Alkazzaz Omar A Shareef and Abdulkhalik S Alkazzaz

Keyword(s):

Density Functional ◽

Ring Closure ◽

Basis Set ◽

Functional Theory ◽

Rate Determining Step ◽

Electronic And Structural Properties ◽

Maximum Hardness Principle

Noble gas cluster ions

EPJ Web of Conferences ◽

10.1051/epjconf/201817406003 ◽

2018 ◽

Vol 174 ◽

pp. 06003

Author(s):

Yunus Kaya ◽

Yalçin Kalkan ◽

Rob Veenhof

Keyword(s):

Density Functional ◽

Noble Gas ◽

Kinetic Studies ◽

Basis Set ◽

Cluster Ions ◽

Functional Theory ◽

B3lyp Method ◽

Xenon Cluster ◽

Potential Basis

In this work, a reaction mechanism of formation of noble gas (Ng) cluster ions has been theoretically investigated in detail. The kinetic studies of formation of Xe+Xe cluster in Xe, Ar+Ar cluster ions in Ar, and Ne+Ne cluster ions in Ne have been made as theoretically. The optimized structures in the ground state were calculated using the density functional theory (DFT) by the B3LYP method combined with the Stuttgart/Dresden effective core potential basis set (SDD). In addition, we calculated the rate constants of all cluster formations. The results are 1.15 × 10−31, 3.58 × 10−31, 0.23 × 10−31cm6/s, respectively for Neon, Argon, Xenon cluster ions.