Quantum mechanical predictions to elucidate the anisotropic elastic properties of zeolitic imidazolate frameworks: ZIF-4 vs. ZIF-zni

CrystEngComm ◽  
2015 ◽  
Vol 17 (2) ◽  
pp. 375-382 ◽  
Author(s):  
Jin-Chong Tan ◽  
Bartolomeo Civalleri ◽  
Alessandro Erba ◽  
Elisa Albanese
Keyword(s):  
Density Functional Theory ◽  
Chemical Composition ◽  
Elastic Properties ◽  
Density Functional ◽  
Quantum Mechanical ◽  
Zeolitic Imidazolate Frameworks ◽  
Functional Theory ◽  
Crystalline Structures ◽  
Negative Poisson's Ratio ◽  
Anisotropic Elastic

We use density functional theory to reveal the detailed elastic properties of two topical ZIF materials comprising the same chemical composition but different crystalline structures. ZIF-4 was found to exhibit a negative Poisson's ratio, representing the first ‘auxetic-ZIF’ to be identified.

scholarly journals First Principles Density Functional Theory Prediction of the Crystal Structure and the Elastic Properties of Mo2ZrB2 and Mo2HfB2

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 865
Author(s):  
Rachid Stefan Touzani ◽  
Manja Krüger
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Elastic Properties ◽  
First Principles ◽  
Density Functional ◽  
Dynamic Instability ◽  
Ternary Alloys ◽  
Functional Theory ◽  
Unknown Density ◽  
Anisotropic Elastic

The Molybdenum rich ternary alloys Mo-M-B (M = Zr, Hf) contain, next to the Mo solid solution (bcc Mo with small amounts of Zr or Hf as substitutional atoms), the binary borides Mo2B, MB and MB2. Recently, it was found that there is also ternary Mo2MB2, but the crystal structure and further properties are currently unknown. Density functional theory (DFT) calculations were used not only to predict the crystal structure of the Mo2MB2 phases, but also to estimate the isotropic and anisotropic elastic properties like bulk, shear and Young’s modulus, as well as the Vickers hardness of these new borides. Several known crystal structures that fulfill the criterion of the chemical composition were investigated, and the AlMn2B2 type structure seems to be the most stable crystal structure for Mo2HfB2 and Mo2ZrB2 as there are no signs of electronic or dynamic instability. Regarding the elastic properties, it was found that Mo2HfB2 shows higher elastic moduli and is less elastically anisotropic than Mo2ZrB2.

Plasmonic resonances of nanoparticles from large-scale quantum mechanical simulations

2017 ◽  
Vol 31 (24) ◽  
pp. 1740003 ◽  
Author(s):  
Xu Zhang ◽  
Hongping Xiang ◽  
Mingliang Zhang ◽  
Gang Lu
Keyword(s):  
Density Functional Theory ◽  
Metallic Nanoparticles ◽  
Density Functional ◽  
Large Scale ◽  
Incident Light ◽  
Time Dependent ◽  
Coherent Motion ◽  
Quantum Mechanical ◽  
Functional Theory ◽  
Conduction Electrons

Plasmonic resonance of metallic nanoparticles results from coherent motion of its conduction electrons, driven by incident light. For the nanoparticles less than 10 nm in diameter, localized surface plasmonic resonances become sensitive to the quantum nature of the conduction electrons. Unfortunately, quantum mechanical simulations based on time-dependent Kohn–Sham density functional theory are computationally too expensive to tackle metal particles larger than 2 nm. Herein, we introduce the recently developed time-dependent orbital-free density functional theory (TD-OFDFT) approach which enables large-scale quantum mechanical simulations of plasmonic responses of metallic nanostructures. Using TD-OFDFT, we have performed quantum mechanical simulations to understand size-dependent plasmonic response of Na nanoparticles and plasmonic responses in Na nanoparticle dimers and trimers. An outlook of future development of the TD-OFDFT method is also presented.

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