Theoretical study of structural, electronic, and optical properties of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi>Zn</mml:mi><mml:mi>m</mml:mi></mml:msub><mml:msub><mml:mi>Se</mml:mi><mml:mi>n</mml:mi></mml:msub></mml:mrow></mml:math>clusters

Goswami, Biplab; Pal, Sougata; Sarkar, Pranab; Seifert, Gotthard; Springborg, Michael

doi:10.1103/physrevb.73.205312

Cited by 40 publications

(36 citation statements)

References 54 publications

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“…Such studies have of course been performed 16,17,21,22 and while the approximations made in TD-DFTB seem drastic at first sight, the overall accuracy of the method has been found to be promising and TD-DFTB has since seen a wide variety of applications. [23][24][25][26][27][28][29][30][31][32] In summary, TD-DFTB is a computationally rather simple approximation to TD-DFT where the computational bottleneck is the size of the response matrix Ω and the calculation of its eigenvectors. In the next section we will present computational methods to solve the TD-DFTB equations efficiently.…”

Section: Td-dft(b)mentioning

confidence: 99%

Efficient Calculation of Electronic Absorption Spectra by Means of Intensity-Selected Time-Dependent Density Functional Tight Binding

Rüger

Lenthe

Lü

et al. 2014

J. Chem. Theory Comput.

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During the last two decades density functional based linear response approaches have become the de facto standard for the calculation of optical properties of small and medium-sized molecules. At the heart of these methods is the solution of an eigenvalue equation in the space of single-orbital transitions, whose quickly increasing number makes such calculations costly if not infeasible for larger molecules. This is especially true for time-dependent density functional tight binding (TD-DFTB), where the evaluation of the matrix elements is inexpensive. For the relatively large systems that can be studied the solution of the eigenvalue equation therefore determines the cost of the calculation. We propose to do an oscillator strength based truncation of the single-orbital transition space to reduce the computational effort of TD-DFTB based absorption spectra calculations. We show that even a * To whom correspondence should be addressed sizeable truncation does not destroy the principal features of the absorption spectrum, while naturally avoiding the unnecessary calculation of excitations with small oscillator strengths. We argue that the reduced computational cost of intensity-selected TD-DFTB together with its ease of use compared to other methods lowers the barrier of performing optical properties calculations of large molecules, and can serve to make such calculations possible in a wider array of applications.

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Section: Td-dft(b)mentioning

confidence: 99%

Efficient Calculation of Electronic Absorption Spectra by Means of Intensity-Selected Time-Dependent Density Functional Tight Binding

Rüger

Lenthe

Lü

et al. 2014

J. Chem. Theory Comput.

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“…eq. (8). The amount of winding taken out is represented by e iqx , where q has so far been left undetermined.…”

Section: Boundary Conditionsmentioning

confidence: 99%

“…One alternative may be to use a discrete model-essentially, a chain of Josephson junctions. Relevance of such models to nanowires has been discussed in [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Metastability and bifurcation in superconducting nanorings

Khlebnikov

2017

Phys. Rev. B

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We describe an approach, based on direct numerical solution of the Usadel equation, to finding stationary points of the free energy of superconducting nanorings. We consider both uniform (equilibrium) solutions and the critical droplets that mediate activated transitions between them. For the uniform solutions, we compute the critical current as a function of the temperature, thus obtaining a correction factor to Bardeen's 1962 interpolation formula. For the droplets, we present a metastability chart that shows the activation energy as a function of the temperature and current. A comparison of the activation energy for a ring to experimental results for a wire connected to superconducting leads reveals a discrepancy at large currents. We discuss possible reasons for it. We also discuss the nature of the bifurcation point at which the droplet merges with the uniform solution.

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“…However, the structural similarity between WZ and ZB and the associated small differences in cohesive energies of the order of few tens of meV/atom make the situation complex. While such an interesting issue has drawn attention in past and have lead to theoretical analysis based on parametrized tight-binding models, 10,11 to our knowledge no rigorous first-principles study exist to address this issue. Very little is also known about the details of the experimental situation, e.g.…”

Section: Introductionmentioning

confidence: 99%

First-Principles Study of Structural Stability and Electronic Structure of CdS Nanoclusters

et al. 2008

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Using first-principles density functional calculations, we have studied the structural stability of stoichiometric as well as non-stoichiometric CdS nanoclusters at ambient pressure with diameters ranging up to about 2.5 nm. Our study reveals that the relative stability of the two available structures for CdS, namely zinc blende and wurtzite, depends sensitively on the details like surface geometry and/or surface chemistry. The associated band gap also exhibits non-monotonic behavior as a function of cluster size. Our findings may shed light on reports of experimentally observed structures and associated electronic structures of CdS nanoclusters found in the literature.

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Theoretical study of structural, electronic, and optical properties ofZnmSenclusters

Cited by 40 publications

References 54 publications

Efficient Calculation of Electronic Absorption Spectra by Means of Intensity-Selected Time-Dependent Density Functional Tight Binding

Efficient Calculation of Electronic Absorption Spectra by Means of Intensity-Selected Time-Dependent Density Functional Tight Binding

Metastability and bifurcation in superconducting nanorings

First-Principles Study of Structural Stability and Electronic Structure of CdS Nanoclusters

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