Electronic, optical and vibrational features of BiVO4 nanostructures investigated by first-principles calculations

RSC Advances ◽  
2016 ◽  
Vol 6 (112) ◽  
pp. 110695-110705 ◽  
Author(s):  
K. Ordon ◽  
A. Kassiba ◽  
M. Makowska-Janusik
Keyword(s):  
Quantum Chemical Calculations ◽  
Surface Reconstruction ◽  
First Principles ◽  
Quantum Chemical ◽  
Numerical Models ◽  
Vibrational Properties ◽  
First Principles Calculations ◽  
Semi Empirical ◽  
Vibrational Features

Numerical models based on DFT and semi-empirical quantum chemical calculations were developed for bulk and nano-sized BiVO4 semiconducting oxide. Importance of surface reconstruction for electronic and vibrational properties was shown.

Why Think Up New Molecules?

2012 ◽  
Author(s):  
Roald Hoffmann
Keyword(s):  
Simple Model ◽  
Human Nature ◽  
Quantum Chemical Calculations ◽  
First Principles ◽  
Quantum Chemical ◽  
Model Building ◽  
Microscopic Level ◽  
First Principles Calculations ◽  
Do So

Some theoreticians in chemistry, myself included, like to think about molecules that do not (yet) exist. I use the simple word “think” advisedly, for the design need not use fancy-schmancy computer-intensive “first-principles” calculations. We conjure up the chemical future in so many ways—simple model building, qualitative thinking, and from ever-more-reliable quantum chemical calculations. Even in dreams, as Henning Hopf reminded me, Kekulé’s ouroboric benzene in mind. But why do we try to imagine new molecules? Aren’t there enough molecules already on earth, be they natural or synthetic? A potpourri of reasons follows. Synthesis, the making of molecules, is at the heart of chemistry—the art, craft, business, and science of substances (molecules at the microscopic level) and their transformations. Of course you need to know what substances are, so analysis is a parallel, lively enterprise. As is figuring out why molecules have the colors or other properties they do, why they react in certain ways and not others. Chemists make the objects of their own contemplation. And, of course, study the beautiful evolved world around and within them. By being as much (if not more) in the work of creation as discovery, chemistry is close to art. And lest we get too puffed up on that, creation brings chemistry also close to engineering (which certainly can have artistic elements in it!). I love explaining. But as a theoretician, I also want to take part in the work of creation. I can do so by thinking up interesting molecules not yet made. Maybe, just maybe, an experimentalist will try to make the molecule. Actually, given human nature, a hypothetical molecule will be made more expeditiously if it is thought up by the synthesizer, rather than by me. Since chemistry is a semi-infinite macrocosm of structure, there are many interesting molecules waiting to be made. And still many more that might as well wait a while longer. Few of the 355 dodecanes (C12H26) are extant. For good reasons—new principles, new properties are most unlikely to be found among them. So it’s not just predicting any molecule that does not exist, it’s predicting one that’s in some way “interesting.” That loose word has both cognitive and emotional sides to it, and is definitely subjective. Nevertheless, I find “interesting” works very well, in evoking the psychological mix that makes the intelligent graduate student’s mind hop to.

First principles calculations of the vibrational properties of single and dimer F-type centers in corundum crystals

2020 ◽  
Vol 153 (13) ◽  
pp. 134107
Author(s):  
Alexander Platonenko ◽  
Denis Gryaznov ◽  
Anatoly I. Popov ◽  
Roberto Dovesi ◽  
Eugene A. Kotomin
Keyword(s):  
First Principles ◽  
Vibrational Properties ◽  
First Principles Calculations

2D-HfS2as an efficient photocatalyst for water splitting

2016 ◽  
Vol 6 (17) ◽  
pp. 6605-6614 ◽  
Author(s):  
Deobrat Singh ◽  
Sanjeev K. Gupta ◽  
Yogesh Sonvane ◽  
Ashok Kumar ◽  
Rajeev Ahuja
Keyword(s):  
Water Splitting ◽  
First Principles ◽  
Vibrational Properties ◽  
First Principles Calculations

Using first principles calculations we have systematically investigated the structural, electronic and vibrational properties of HfS2monolayers in both hexagonal (1H) and trigonal (1T) phases.

Vibrational Properties of Metal Phosphorus Trichalcogenides from First-Principles Calculations

2017 ◽  
Vol 121 (48) ◽  
pp. 27207-27217 ◽  
Author(s):  
Arsalan Hashemi ◽  
Hannu-Pekka Komsa ◽  
Martti Puska ◽  
Arkady V. Krasheninnikov
Keyword(s):  
First Principles ◽  
Vibrational Properties ◽  
First Principles Calculations

Structural phase transition, electronic, elastic, and vibrational properties of LiAl intermetallic compound: insights from first-principles calculations

2017 ◽  
Vol 95 (8) ◽  
pp. 691-698
Author(s):  
Y. Mogulkoc ◽  
Y.O. Ciftci ◽  
G. Surucu
Keyword(s):  
Phase Transition ◽  
Density Of States ◽  
Structural Phase Transition ◽  
First Principles ◽  
Density Functional ◽  
Structural Phase ◽  
Type Structure ◽  
Vibrational Properties ◽  
First Principles Calculations ◽  
Electronic Band

Using the first-principles calculations based on density functional theory (DFT), the structural, elastic, electronic, and vibrational properties of LiAl have been explored within the generalized gradient approximation (GGA) using the Vienna ab initio simulation package (VASP). The results demonstrate that LiAl compound is stable in the NaTl-type structure (B32) at ambient pressure, which is in good agreement with the experimental results and there is a structural phase transition from NaTl-type structure (B32) to CsCl-type structure (B2) at around 22.2 GPa pressure value. The pressure effects on the elastic properties have been discussed and the elastic property calculation indicates that the elastic instability could provide a phase transition driving force according to the variations relation of the elastic constant versus pressure. To gain further information about this, we also have investigated the other elastic parameters (i.e., Zener anisotropy factor, Poisson’s ratio, Young’s modulus, and isotropic shear modulus). The electronic band structure, total and partial density of states, phonon dispersion curves, and one-phonon density of states of B2 and B32 phases are also presented with results.

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