Questions tagged [surfaces]

For questions around the modeling and description of materials surfaces

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5
votes
1answer
53 views

Divergence behaviour of surface energy

By definition, the surface energy of a thin film or a slab model is defined as $$ \sigma = \frac{1}{2A}(E_{slab} - N\cdot E_{bulk}) $$ where $N$ is the number of atoms in the thin film and $E_{bulk}$ ...
6
votes
1answer
64 views

Calculating the surface state with Wannier tools

Currently I met a problem when I calculate the surface state of a topologically non-trivial thin film system. I did a DFT calculation and fit the result with wannier function. The fitting looks pretty ...
4
votes
1answer
36 views

SiC surface reconstruction

I know how to cleave surfaces with integer Miller indices, however I wonder how I could cleave a $(\sqrt{3} \times \sqrt{3}) R30$ reconstruction of $(001)\,\, 4H-SiC$. I have found a nice link to O-...
11
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1answer
44 views

How can I properly attach ligands to a surface?

The main aim of my venture is to study the effect of the presence of surface ions on the band structure of Si slab using Quantum ESPRESSO. I've tried to use iQmol to attach ligands to the surface. The ...
5
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0answers
44 views

Is it necessary to terminate the surface ions in a quantum dot?

I was trying to study quantum dots of ZnO. But I'm pretty new to creating and passivating 0 D particles. Is it always necessary to passivate the free surface of the quantum dot? Regarding the studies ...
7
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1answer
94 views

How to build the [111] slab model of NiSe2 with different terminations with ASE tool?

The following figure is the bulk structure of NiSe$_2$ downloaded from the materials project database. Now I want to study the properties of its [111] plane. In detial, I cut the slab with atomic ...
12
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0answers
97 views

How do I know if the reconstruction in the picture is a 2 x 2 reconstruction?

How do I know if the reconstruction in the picture is a 2 x 2 reconstruction or not?                                     I believe that this corresponds to a 2x2 reconstruction because there's an even ...
18
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4answers
1k views

How to explain Miller indices to someone outside nanomaterials?

I often find that when talking to experimentalists outside of the field of nanomaterials, it is nearly impossible to explain Miller indices concisely. As this often comes up during talks from other ...
8
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1answer
103 views

Electron Affinity of Semiconductors via DFT

Can we calculate electron affinity of a semiconductor (e.g., for Si) using density functional theory calculations in VASP? Which calculations are needed to compute electron affinity and band offsets?
8
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1answer
56 views

Working with charged surfaces

A previous question addressed how to deal with charge defects in bulk materials. What can be done to treat a 2D surface with respect to charge? For example, how can an absorption energy of OH- on Pt(...
12
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2answers
458 views

What is Surface termination and how to make surface termination of a crystal structure?

I want to calculate the surface energy of CuO and for that, I've asked CuO (monoclinic) crystallographic plane and their relaxed surface energy. But for the lack of knowledge of the surface ...
13
votes
1answer
115 views

What progress has been made in modelling photocatalytic reactions on semiconductor surfaces?

For example, are there any methods to allow for modeling of photo-oxidation or photo-reduction of a compound on a semiconductor surface? It appears there has been a lot of work on the bulk properties ...
12
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0answers
107 views

Sample LAMMPS file for graphene growth on a metal surface

I am working with graphene growth on metal substrates. But I need some sample files to know if I am doing it in the right way because running multiple simulations in LAMMPS takes a lot of time. Can ...
5
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0answers
48 views

Key points for studying surfaces intended for researchers on gas phase [closed]

A common situation is that researches move slightly from their expertise area. In those cases, the tutorials for beginners are not suitable. A common doubt is "This is reasonable, I am sure but: ...
7
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1answer
68 views

How to calculate the energy of a surface?

I want to study the interaction of a surface with some molecules (green house effect gases). To obtain the binding energy, the procedure is to calculate the energy of both systems separately $E_\...
13
votes
1answer
140 views

What are the steps to prepare a surface for molecular adsorption simulations on it?

I want to study the interaction of a given surface with some molecules. How should I prepare the surface for that kind of simulation? By prepare the surface I mean how many atom layers, how many of ...
16
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1answer
72 views

Protein cavities - methodological starting point for basic characterization

Characterizing surface properties is important for understanding how proteins execute their function by interacting with other molecules. This includes characterizing cavities. Perhaps the simplest ...
15
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2answers
103 views

How to model a random distribution of molecules attached to a surface?

In the same aspect as some of my previous questions, I am interested in modeling molecules on different surfaces and to study the interfacial effect on them. One of the most important problems that ...
17
votes
1answer
118 views

Fermi level change in surfaces with adsorbed molecules

In a DFT standard calculation of a solid 3D material (i.e. bulk metal), one of the properties that can be obtained is the Fermi level $E_F$. This feature is related with the required work to add an ...
19
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2answers
143 views

How to model heterogeneous catalysis?

Heterogeneous catalysis is known to be very important: Approximately 35% of the world's GDP is influenced by catalysis. The production of 90% of chemicals (by volume) is assisted by solid catalysts....
16
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3answers
339 views

Computational tools for automatic creation of surface slab models of complex systems

I am looking for computational tools that can be used to automatize the generation surface slab models of latices of oxides, layered oxides, perovskites etc. I have found a promising Python package, ...
14
votes
1answer
45 views

The upper limit for the atomic adsorption energy value on a slab surface?

I want to adsorb atomic oxygen on a slab surface. The adsorption energy I am calculating is around -10 eV. Which seems higher to me than I expected. My question is this: Is this value reasonable ...
20
votes
3answers
191 views

Generating special quasirandom structures (SQS) for surface calculations?

Given that most of the available codes for performing DFT calculations work with periodic boundary conditions, there are tools like mcsqs as a part of the Alloy ...
18
votes
1answer
105 views

Are plane-wave basis sets reliable for modeling adsorption processes?

Plane-wave basis sets are useful in the calculation of periodic systems and can be used in combination with pseudopotentials. However, when dealing with surfaces the system is no longer periodic in, ...