Questions tagged [density-functional-theory]

For questions about simulations using Density Functional Theory.

22 questions with no upvoted or accepted answers
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12
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Promising functionals for transition metal chemistry

I'm looking to get your opinions on the most promising density functionals to use for thermochemistry and kinetics of transition metal complexes. However, as eloquently laid out by Tom Manz on this ...
10
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0answers
113 views

What can we learn by inspecting charge densities calculated with DFT?

The charge density is an important physical quantity obtained from first-principles calculations based on density functional theory (DFT). Much useful information about the investigated materials can ...
10
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0answers
48 views

Why are single excitations ignored in the MP2 component of double hybrid functional calculations?

In the original paper by Grimme introducing double hybrid functionals (also summarized in just 3 paragraphs here), it says: "[As] opposed to nonempirical versions of KS-PT2 [19], the single ...
9
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0answers
56 views

Problem related to the calculation of elastic constant with VASP5.4.4

I am using VASP5.4.4 to calculate the mechanical properties of the cubic phase SnTe. The structure can be found in the materials project website. In detail, I use the following INCAR to calculate the ...
8
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0answers
47 views

How to interpret second order perturbation theory analysis from NBO calculations?

The question is quite simple — how to interpret NBO results of second order perturbation theory analysis? As I have read several papers the most important interactions are $\pi\rightarrow\pi^{*}$, $LP\...
8
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0answers
39 views

How to predict new Half Metallic materials with higher degree of spin polarization?

Using DFT calculations, how one can predict the new half metallic materials with higher degree of spin polarization. I want to know the steps which have to be followed in prediction of new materials. ...
8
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0answers
61 views

VASP's NPAR and KPAR for parallelization

What's the best way for parallelization in VASP for periodic systems? In the documentation, it mostly explains it for the local computer and molecule calculation. Apparently, these explanations don't ...
8
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0answers
47 views

Inconsistent data of chemical potential from different papers

I am looking for chemical potential from literature: ...
8
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0answers
61 views

I ran TDDFT on some small molecules. For some files, the ORCA output files cut short and contain no absorption data. What could be the reason?

Below is just the end of the output file, and the top of the input file. This is for the molecule FDICTF. The calculation did not run out of time. I ran a batch of 15 molecules, all with same ...
8
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0answers
61 views

Is the non-trivial band topology in a system, caused by spin-orbit-coupling or band inversion?

How can we know that the non-trivial band topology in a system is driven by spin-orbit coupling (SOC) or by band inversion? Based on my understanding, SOC causes the band inversion and makes the ...
7
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0answers
38 views

Converge number of layers of atoms or number of unit cells for adsorption calculations?

I'm trying to calculate the adsorption energies of various adsorbates on Fe2O3 surfaces (although, with there being many possible surfaces for Fe2O3 it is quite complex, but that's for another time...)...
7
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0answers
23 views

how to create an effective INCAR setting in VASP for a heterostructure calculation

I am a beginner of using VASP to do material Modelling. I have made a heterostructure model written in the form of POSCAR file. But the supercell is too big (it contains 60 atom) so that the ...
7
votes
1answer
69 views

What is the physical meaning of occupations='smearing' in Quantum ESPRESSO?

I want to understand, what is the intuition behind using the occupations='smearing' or 'tetrahedra' in Quantum ESPRESSO input file? I mean how we can interpret what is going to happen inside of ...
7
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0answers
31 views

Why are there some residual magnetic moment on the zigzag graphene nanoribbon passivated with H atom?

I am considering the relaxation for the following zigzag graphene nanoribbon. Here the boundary of the zigzag graphene(C: brown) nanoribbon has been passivated with one H atom. I have performed the ...
7
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0answers
34 views

How to do a Delta SCF calculation using ABINIT?

I am trying to optimize the crystal structure based on Delta SCF. But I am not so familiar with ABINIT at all. As the ABINIT website do not provide further information. It would be super nice if ...
7
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0answers
31 views

How does MBD (MBD-NL) differ from DFT-TS?

Is anyone familiar with the Tkatchenko's new MBD-NL method? How does it differ from DFT-TS? I couldn't understand everything from the paper.
7
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0answers
57 views

What are the advantages/disadvantages of QMC over ACFDT-RPA?

I had some experience with the ACFDT-RPA, despite its promising features it's not practical most of the times, and for that reason, I'm looking for a new method for reference calculations. QMC is the ...
7
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0answers
62 views

ASE's fmax and FHI-AIMS's relax_geometry bfgs “tolerance”. Are they same?

They look like the same thing, but their definitions are confusing. Additionally, while it's possible to use 'tolerance'< 0.05 in AIMS easily, in ASE, some structures never optimize if you choose ...
7
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0answers
47 views

Orbital-free DFT and Density Functional Tight-Binding: Comparison

There are many flavors of DFT that are alternative or go beyond the formulation of Kohn and Sham (KS-DFT). Some of these are based on approximations that sacrifice accuracy when compared to KS-DFT, ...
5
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0answers
94 views

Is there any way to simulate the Polarization vs Electric Field loop of BaTiO3 using Quantum ESPRESSO?

I'm new to the Quantum ESPRESSO package. There are articles outlining the procedure of indirectly simulating the P-E loop of piezo-electric materials via berry phase calculations.One procedure is ...
5
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0answers
34 views

Structural biology vs condensed matter prediction

I have two main modeling research lines: one related to structural biology (including rational drug design, de novo design, polymorphism, etc.) and the other one related to condensed matter (...
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0answers
10 views

Isotopes in Reaction Kinetics by Transition State Theory

Can kinetic isotope effects be handled in density functional theory level calculations? My intuition says that in the context of molecular dynamics simulations that they can be, but can transition ...