scholarly journals Role of van der Waals bonding in the layered oxideV2O5: First-principles density-functional calculations

2010 ◽  
Vol 82 (5) ◽  
Author(s):  
Elisa Londero ◽  
Elsebeth Schröder
Keyword(s):  
First Principles ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Van Der Waals

Thermodynamic Stability of Hexagonal and Rhombohedral Bn at Cvd Conditions from Van der Waals Corrected First Principles Calculations

2019 ◽  
Author(s):  
Henrik Pedersen ◽  
Björn Alling ◽  
Hans Högberg ◽  
Annop Ektarawong
Keyword(s):  
Thin Films ◽  
Thermodynamic Stability ◽  
First Principles ◽  
Thermal Equilibrium ◽  
Density Functional ◽  
Van Der Waals ◽  
Chemical Vapor ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Stability

Thin films of boron nitride (BN), particularly the sp<sup>2</sup>-hybridized polytypes hexagonal BN (h-BN) and rhombohedral BN (r-BN) are interesting for several electronic applications given band gaps in the UV. They are typically deposited close to thermal equilibrium by chemical vapor deposition (CVD) at temperatures and pressures in the regions 1400-1800 K and 1000-10000 Pa, respectively. In this letter, we use van der Waals corrected density functional theory and thermodynamic stability calculations to determine the stability of r-BN and compare it to that of h-BN as well as to cubic BN and wurtzitic BN. We find that r-BN is the stable sp<sup>2</sup>-hybridized phase at CVD conditions, while h-BN is metastable. Thus, our calculations suggest that thin films of h-BN must be deposited far from thermal equilibrium.

uMBD: A Materials-Ready Dispersion Correction that Uniformly Treats Metallic, Ionic, Covalent, and van der Waals Bonding

2019 ◽  
Author(s):  
Minho Kim ◽  
won june kim ◽  
Tim Gould ◽  
Eok Kyun Lee ◽  
Sébastien Lebègue ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Electrode Materials ◽  
Full Range ◽  
Van Der Waals ◽  
Dft Method ◽  
Dispersion Correction ◽  
Computational Overhead ◽  
System A ◽  
Battery Design

<p>Materials design increasingly relies on first-principles calculations for screening important candidates and for understanding quantum mechanisms. Density functional theory (DFT) is by far the most popular first-principles approach due to its efficiency and accuracy. However, to accurately predict structures and thermodynamics, DFT must be paired with a van der Waals (vdW) dispersion correction. Therefore, such corrections have been the subject of intense scrutiny in recent years. Despite significant successes in organic molecules, no existing model can adequately cover the full range of common materials, from metals to ionic solids, hampering the applications of DFT for modern problems such as battery design. Here, we introduce a universally optimized vdW-corrected DFT method that demonstrates an unbiased reliability for predicting molecular, layered, ionic, metallic, and hybrid materials without incurring a large computational overhead. We use our method to accurately predict the intercalation potentials of layered electrode materials of a Li-ion battery system – a problem for which the existing state-of-the-art methods fail. Thus, we envisage broad use of our method in the design of chemo-physical processes of new materials.</p>

scholarly journals Study of odd–even effects in physisorption and chemisorption of Ar, N2, O2 and NO on open shell Ag11–13+ clusters by means of self-consistent van der Waals density functional calculations

2019 ◽  
Vol 21 (45) ◽  
pp. 25158-25174
Author(s):  
Eva M. Fernández ◽  
Luis C. Balbás
Keyword(s):  
Small Molecules ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Van Der Waals ◽  
Open Shell ◽  
Self Consistent

Electronic and structural odd-even effects in the adsorption of small molecules on open shell silver cationic clusters have been rationalized.

Electronic Structure and Hydrogen Desorption in NaAlH4

2004 ◽  
Vol 837 ◽  
Author(s):  
S. Li ◽  
P. Jena ◽  
C. M. Araujo ◽  
R. Ahuja
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Metal Hydrides ◽  
Hydrogen Desorption ◽  
Light Metal ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Design And Synthesis

ABSTRACTFirst principles calculations based on gradient corrected density functional theory are carried out to understand the electronic structure and mechanisms responsible for desorption of hydrogen from Ti doped and vacancy containing sodium-alanate (NaAlH4). The energy necessary to remove a hydrogen atom from Ti doped NaAlH4 is significantly smaller than that from pristine NaAlH4 irrespective of whether Ti substitutes the Na or the Al site. However, the presence of Na and Al vacancies is shown to play an even more important role: The removal of hydrogen associated with both Na and Al vacancies is found to be exothermic. It is suggested that this role of vacancies can be exploited in the design and synthesis of complex light metal hydrides suitable for hydrogen storage.

The Studies of ScB2 (0001) Surfaces from the First-Principles

2014 ◽  
Vol 989-994 ◽  
pp. 688-693
Author(s):  
Hui Zhao ◽  
Qian Han
Keyword(s):  
Energy Density ◽  
Total Energy ◽  
Electronic Properties ◽  
First Principles ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Surface Structures ◽  
Charge Accumulation ◽  
Total Energy Density ◽  
Energy Density Functional

We conduct first-principles total-energy density functional calculations to study the ScB2 (0001) surfaces. The optimized surface structures and electronic properties are obtained. The results show that Sc-terminated surface is thermodynamically more favorable in most of range. The relaxations indicate that it is mainly localized within top three layers and it is less relaxation for Sc-terminated surface. The surface induced features in DOS disappear slowly for the B-terminated surface but vanish rapidly for the Sc-terminated surface. For the Sc-terminated surface, it shows strong metallic property. Simultaneously, both termination surfaces are found charge accumulation relative to the idea surface. Sc-B bonds are strengthened result in the outermost interface spacing are all contracted.

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