55 research outputs found
Exploring the role of electronic structure on photo-catalytic behavior of carbon-nitride (C3N4) polymorphs
Get PDFA fully self-consistent density-functional theory (DFT) with improved functionals is used to provide a comprehensive account of structural, electronic, and optical properties of C3N4 polymorphs. Using our recently developed van Leeuwen-Baerends (vLB) corrected local-density approximation (LDA), we implemented LDA + vLB within full-potential Nth-order muffin-tin orbital (FP-NMTO) method and show that it improves structural properties and band gaps compared to semi-local functionals (LDA/GGA). We demonstrate that the LDA + vLB predicts band-structure and work-function for well-studied 2D-graphene and bulk-Si in very good agreement with experiments, and more exact hybrid functional (HSE) calculations as implemented in the Quantum-Espresso (QE) package. The structural and electronic-structure (band gap) properties of C3N4 polymorphs calculated using FP-NMTO-LDA + vLB is compared with more sophisticated hybrid-functional calculations. We also perform detailed investigation of photocatalytic behavior using QE-HSE method of C3N4 polymorphs through work-function, band (valence and conduction) position with respect to water reduction and oxidation potential. Our results show γ-C3N4 as the best candidate for photocatalysis among all the C3N4 polymorphs but it is dynamically unstable at ‘zero’ pressure. We show that γ-C3N4 can be stabilized under hydrostatic-pressure, which improves its photocatalytic behavior relative to water reduction and oxidation potentials.This is a manuscript of the article Datta, Sujoy, Prashant Singh, Debnarayan Jana, Chhanda B. Chaudhuri, Manoj K. Harbola, Duane D. Johnson, and Abhijit Mookerjee. "Exploring the role of electronic structure on photo-catalytic behavior of carbon-nitride polymorphs." Carbon (2020). DOI: 10.1016/j.carbon.2020.04.008. Posted with permission.</p
Nova regulacijska shema
Get PDFWe develop the mode-matching regularization scheme particularly suitable for problems in a uniform magnetic field. We apply this regularization scheme to bare QED vacuum in (2+1) dimensions. This regularization scheme gives the exact renormalization of the bare QED vacuum and establishes its diamagnetic nature.Razvili smo regulacijsku shemu s usklađivanjem modova koja je posebno pogodna za probleme u jednolikom magnetskom polju. Primijenili smo je u prostoru s (2+1) dimenzija i čistom QED vakuumu. Ova regulacijska shema daje egzaktnu renormalizaciju čistog vakuuma i utvrđuje njegovu dijamagnetsku narav
Preskočna vodljivost uzrokovana magnetskim poljem u sustavu s pseudo-procijepom
Get PDFWe present a simple scaling form of Mott conductivity formula in case of amorphous material in presence of an external magnetic field in an arbitrary spatial dimension d. The model of the interacting system is chosen as the variable range hopping (VRH) one with density of states having a soft gap at the Fermi energy. We indicate the relation between the conductivity exponents (both in weak and strong magnetic field) with that without the magnetic field. The exponents related to the variation of activation energy with temperature have also been computed. We also indicate the lower as well as the upper bound of the conductivity exponents. Besides, a connecting formula between the exponents (non-interacting, interacting with weak magnetic field and interacting with strong magnetic field) shows that only two of them are independent. Previously-known results can be obtained from this generalized form of the conductivity. Finally, a comparison of the exponents has been done with the strong electric field case.Opisuje se jednostavan izraz za sumjeravanje za Mottov izraz za vodljivost u amorfnim tvarima u vanjskom magnetskom polju uz proizvoljnu prostornu dimenziju d. Kao model odabrano je međudjelovanje preskakivanjem promjenljivog dosega u sustavu s mekim procijepom na Fermijevoj energiji. Pokazujemo odnos eksponenata vodljivosti bez magnetskog polja s onima u slabom i jakom magnetskom polju. Izračunali smo također eksponente u svezi s promjenama aktivacijske energije s temperaturom. Pokazuju se donje i gornje granice eksponenata vodljivosti. Relacija među eksponentima (bez međudjelovanja, te s međudjelovanjem u slabom i u jakom magnetskom polju) pokazuje da su samo dva eksponenta nezavisna. Od ranije poznati podaci mogu se izvesti iz novog izraza za vodljivost. Na kraju se daje usporedba eksponenata s onima za slučaj snažnog električnog polja
Nova regulacijska shema
Get PDFWe develop the mode-matching regularization scheme particularly suitable for problems in a uniform magnetic field. We apply this regularization scheme to bare QED vacuum in (2+1) dimensions. This regularization scheme gives the exact renormalization of the bare QED vacuum and establishes its diamagnetic nature.Razvili smo regulacijsku shemu s usklađivanjem modova koja je posebno pogodna za probleme u jednolikom magnetskom polju. Primijenili smo je u prostoru s (2+1) dimenzija i čistom QED vakuumu. Ova regulacijska shema daje egzaktnu renormalizaciju čistog vakuuma i utvrđuje njegovu dijamagnetsku narav
Preskočna vodljivost uzrokovana magnetskim poljem u sustavu s pseudo-procijepom
Get PDFWe present a simple scaling form of Mott conductivity formula in case of amorphous material in presence of an external magnetic field in an arbitrary spatial dimension d. The model of the interacting system is chosen as the variable range hopping (VRH) one with density of states having a soft gap at the Fermi energy. We indicate the relation between the conductivity exponents (both in weak and strong magnetic field) with that without the magnetic field. The exponents related to the variation of activation energy with temperature have also been computed. We also indicate the lower as well as the upper bound of the conductivity exponents. Besides, a connecting formula between the exponents (non-interacting, interacting with weak magnetic field and interacting with strong magnetic field) shows that only two of them are independent. Previously-known results can be obtained from this generalized form of the conductivity. Finally, a comparison of the exponents has been done with the strong electric field case.Opisuje se jednostavan izraz za sumjeravanje za Mottov izraz za vodljivost u amorfnim tvarima u vanjskom magnetskom polju uz proizvoljnu prostornu dimenziju d. Kao model odabrano je međudjelovanje preskakivanjem promjenljivog dosega u sustavu s mekim procijepom na Fermijevoj energiji. Pokazujemo odnos eksponenata vodljivosti bez magnetskog polja s onima u slabom i jakom magnetskom polju. Izračunali smo također eksponente u svezi s promjenama aktivacijske energije s temperaturom. Pokazuju se donje i gornje granice eksponenata vodljivosti. Relacija među eksponentima (bez međudjelovanja, te s međudjelovanjem u slabom i u jakom magnetskom polju) pokazuje da su samo dva eksponenta nezavisna. Od ranije poznati podaci mogu se izvesti iz novog izraza za vodljivost. Na kraju se daje usporedba eksponenata s onima za slučaj snažnog električnog polja
Optical properties of monolayer BeC under an external electric field: A DFT approach
No full textAbstract
BeC, a two-dimensional hypercoordinated nanostructure carbon compound, has been the focus of the nanoworld because of its high value of dynamical stability, in-plane stiffness, carrier mobility and the existence of band gap. In this work, we have explored the electronic and the optical properties of this material under the influence of static external perpendicular electric field within the framework of density functional theory. Under the influence of a uniform electric field, the band gap changes within the meV range. The electron energy loss function study reveals that this material has optical band gaps which remain constant irrespective of the applied electric field strength. The optical property also exhibits interesting features when the applied field strength is within 0.4–0.5 V/Å. We have also tried to explain the optical data from the respective band structures and thus paving the way to understand qualitatively the signature of the optical anisotropy from the birefringence study.</jats:p
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