Analyzing the frequency shift of physiadsorbed CO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>in metal organic framework materials

Yao, Yanpeng; Nijem, Nour; Li, Jing; Chabal, Yves J.; Langreth, David C.; Thonhauser, Timo

doi:10.1103/physrevb.85.064302

Cited by 48 publications

(55 citation statements)

References 44 publications

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“…Importantly, it also captures the more general problem when nonlocal correlation forces compete with other types of forces [9], for example, giving rise to binding across important regions of low electron densities [10,14]. The method was expected to be relevant in first-principles DFT for both pure vdW problems including regular physisorption [49,[78][79][80], porous-materials gas absorption [81][82][83][84][85][86][87][88][89][90], and DNA base-pair interactions [91][92][93][94][95]. It was also quickly realized that truly nonlocal correlations affect materials descriptions much more broadly than what was perhaps originally anticipated [10,14,57,77,[96][97][98][99][100].…”

Section: -3mentioning

confidence: 99%

Finite-temperature properties of nonmagnetic transition metals: Comparison of the performance of constraint-based semilocal and nonlocal functionals

Gharaee¹,

Erhart²,

Hyldgaard³

2017

Phys. Rev. B

100

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We assess the performance of nonempirical, truly nonlocal, and semilocal functionals with regard to structural and thermal properties of 3d, 4d, and 5d nonmagnetic transition metals. We focus on constraint-based functionals and consider the consistent-exchange van der Waals density-functional version vdW-DF-cx [Phys. Rev. B 89, 035412 (2014) (2005)]. Using the quasiharmonic approximation, the structural parameters, elastic response, and thermal expansion at finite temperatures are computed and compared to experimental data. We also compute cohesive energies explicitly including zero-point vibrations. It is shown that overall vdW-DF-cx provides an accurate description of thermal properties and retains a level of transferability and accuracy that is comparable to or better than some of the best constraint-based semilocal functionals. Especially, with regard to the cohesive energies, the consistent inclusion of spin-polarization effects in the atoms turns out to be crucial, and it is important to use the rigorous spin-vdW-DF-cx formulation [Phys. Rev. Lett. 115, 136402 (2015)]. This demonstrates that vdW-DF-cx has general-purpose character and can be used to study systems that have both sparse and dense electron distributions.

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Section: -3mentioning

confidence: 99%

Finite-temperature properties of nonmagnetic transition metals: Comparison of the performance of constraint-based semilocal and nonlocal functionals

Gharaee¹,

Erhart²,

Hyldgaard³

2017

Phys. Rev. B

100

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“…31,32 We have already successfully applied vdW-DF to investigate the adsorption of small molecules in MOFs and nano-structures in numerous other studies. 7,8,[33][34][35][36][37][38][39][40] Projector augmentedwave theory, 41,42 combined with a well-converged planewave cutoff of 600 eV, were used to describe the wave functions. The total energy was sampled on a 2×2×2 k -point grid, resulting in four irreducible k -points, necessary to fully converge the stress tensor.…”

Section: Technical Details a Computational Detailsmentioning

confidence: 99%

Structural, elastic, thermal, and electronic responses of small-molecule-loaded metal–organic framework materials

Canepa

Tan

et al. 2015

J. Mater. Chem. A

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We combine infrared spectroscopy, nano-indentation measurements, and ab initio simulations to study the evolution of structural, elastic, thermal, and electronic responses of the metal organic framework MOF-74-Zn when loaded with H2, CO2, CH4, and H2O. We find that the molecular adsorption in this MOF triggers remarkable responses in all of these properties of the host material, with specific signatures for each of the guest molecules. With this comprehensive study we are able to clarify and correlate the underlying mechanisms regulating these responses with changes of the physical and chemical environment. Our findings suggest that metal organic framework materials in general, and MOF-74-Zn in particular, can be very promising materials for novel transducers and sensor applications, including highly selective small-molecule detection in gas mixtures.

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“…To correctly capture the weak van der Waals forceswhich are critical in this study-we use the truly nonlocal functional vdW-DF [14][15][16], which has already been successfully applied to a number of related studies [17][18][19][20][21]. We use ultrasoft pseudopotentials with wavefunction and density cutoffs of 480 eV and 4800 eV, respectively.…”

mentioning

confidence: 99%

Diffusion of Small Molecules in Metal Organic Framework Materials

et al. 2013

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Ab initio simulations are combined with in situ infrared spectroscopy to unveil the molecular transport of H2, CO2, and H2O in the metal organic framework MOF-74-Mg. Our study uncovers-at the atomistic level-the major factors governing the transport mechanism of these small molecules. In particular, we identify four key diffusion mechanisms and calculate the corresponding diffusion barriers, which are nicely confirmed by time-resolved infrared experiments. We also answer a longstanding question about the existence of secondary adsorption sites for the guest molecules, and we show how those sites affect the macroscopic diffusion properties. Our findings are important to gain a fundamental understanding of the diffusion processes in these nano-porous materials, with direct implications for the usability of MOFs in gas sequestration and storage applications. [5,6], MOFs are also interesting for carbon-capture applications. These qualities, combined with their low production cost, have made MOFs the target of many studies, focusing mostly on their adsorption properties [2, 3,[7][8][9]. However, their performance for practical storage and capture applications also critically depends on the diffusion and interaction of gases (e.g. with water) in the MOF environment, which are currently poorly understood [6,10,11].To address this issue and elucidate the diffusion process of small molecules in the nano-pores of MOFs, we use a combination of ab initio simulations and in situ infrared (IR) spectroscopy. Specifically, we study the diffusion of H 2 , CO 2 , and H 2 O in MOF-74-Mg and investigate the role of water on diffusion of small molecules. We focus on this particular MOF, as it has attracted a lot of attention due to its enhanced reactivity with small molecules, caused by the exposure of open metal sites in its nano-pores. Britt et al. [6] have shown that MOF-74-Mg is extremely efficient in capturing CO 2 , compared to iso-structural MOFs with other metal sites such as Zn, Mn, Fe, Co, Ni, and Cu.To model the molecular diffusion in the MOF structure, we use climbing-image nudged elastic band [12] (NEB) simulations coupled with density functional theory (DFT), as implemented in QuantumEspresso [13]. To correctly capture the weak van der Waals forceswhich are critical in this study-we use the truly nonlocal functional vdW-DF [14][15][16], which has already been successfully applied to a number of related studies [17][18][19][20][21]. We use ultrasoft pseudopotentials with wavefunction and density cutoffs of 480 eV and 4800 eV, respectively. Tests show that Γ-point calculations are sufficient and yield total energies converged to within 5 meV with respect to denser k -point meshes; however, energy differences-important for our diffusion barriersare converged to within less than 1 meV. The selfconsistency tolerance was set to 1.4 × 10 −10 eV and during optimizations the total forces were relaxed to less than 2.6 × 10 −4 eV/Å. We started from the experimental MOF-74-Mg structure, optimizing the internal parameters and keep...

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Analyzing the frequency shift of physiadsorbed CO2in metal organic framework materials

Cited by 48 publications

References 44 publications

Finite-temperature properties of nonmagnetic transition metals: Comparison of the performance of constraint-based semilocal and nonlocal functionals

Finite-temperature properties of nonmagnetic transition metals: Comparison of the performance of constraint-based semilocal and nonlocal functionals

Structural, elastic, thermal, and electronic responses of small-molecule-loaded metal–organic framework materials

Diffusion of Small Molecules in Metal Organic Framework Materials

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