Questions tagged [pseudopotentials]

Refers to the approximation of core electrons by effective potentials. Used in plane-wave and Gaussian based theories.

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6
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1answer
51 views

Quantum Espresso energy cutoff for different pseudopotential

I've been told that I should use the potentials from the Standard Solid-State Pseudopotential (SSSP) library in my simulations. I am interested in $\ce{Pt}$, $\ce{O}$, and $\ce{H}$. Oxygen is ...
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1answer
95 views

VASP GW PAW Pseudopotentials

What is the difference between the GW and non-GW potentials in VASP. While it is clear that the GW potentials should be used with GW calculations, the documentation also states that these potentials ...
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133 views

Recommendations to treat 4f electrons (valence) of Yb3+ in magnetic systems in VASP

I need help with: I would like to know what is the most common approach to treat valence 4f electrons of lanthanides (3+ charge) in VASP that circumvents the calculation problems shown below. (or more ...
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86 views

Error in nscf calculation while considering Spin Orbit Coupling in Quantum ESPRESSO

I am trying to do the band structure calculation considering the Spin Orbit Coupling but getting the following error: ...
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2answers
1k views

What is a Padé approximant?

I have been looking at using Goedecker-Teter-Hutter (GTH) pseudo-potentials and I came across the abbreviation PADE. I was wondering what this abbreviation actually stood for and how it is related to ...
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41 views

What does the "pn" column mean in this pseudopotential file?

In this SSSP pseudopotential file for Quantum ESPRESSO, what does the "pn" column mean?
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156 views

Linearized Augmented Plane Wave Method vs. Pseudopotential Methods

While reviewing some DFT literature, I have come across a few papers utilizing the LAPW (Linearized Augmented Plane Wave) method, but I am interested in understanding why exactly one would use these ...
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37 views

Convert PSP8 pseudopotential files to UPF format

Is there a way to convert psp8 pseudopotential files (used for abinit) to UPF format (used for Quantum ESPRESSO)? I noticed there is the upfconv.x utility in ...
14
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1answer
139 views

Why are Norm-conserving Pseudopotentials considered so important?

So I am aware that a norm-conserving pseudopotential enforces the conditions that: Inside the cut-off radius, the norm of each pseudo-wavefunction is identical to its corresponding all-electron ...
12
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2answers
82 views

What are some of the advantages and disadvantages when using shape consistent pseudopotentials as compared to energy consistent pseduopotentials

From the literature as well as the answer to the question What is the meaning of energy-consistent and shape-consistent in the context of pseudopotentials? I can see that the key difference between ...
6
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1answer
105 views

What is the meaning of energy-consistent and shape-consistent in the context of pseudopotentials?

I am trying to use pseudopotentials to model scattering from heavy molecules. However, I am confused by some of the terminologies of pseudopotentials/ECPs: Norm-conserving according to Wikipedia and ...
17
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3answers
270 views

When should I include semi-core electrons in DFT calculations?

Many DFT codes use pseudopotentials (for the core electrons) and basis set functions (for the valence electrons) in order to solve the Schrodinger equation. This because simulates each electron ...
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351 views

When are atomic-orbital-basis (rather than plane-wave) methods appropriate in periodic DFT?

For example, GPAW supports both plane-wave and atomic-orbital basis methods. I know that atomic-orbital basis methods can have difficulty with electrons occupying vacancies for example, but what ...
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434 views

For which elements should I include spin orbit coupling in Quantum ESPRESSO?

I'm trying to study a Yb-Ge-Sb compound and would like to include spin-orbit coupling (SOC). In Quantum ESPRESSO, this is done by including the following tags in the ...
14
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1answer
99 views

Analytical expression for an atomic lattice "muffin-tin" potential for purposes of illustration and simple scattering calculations

Before taking the deep dive (see linked questions below) into calculating the diffraction of 20 to 200 eV electrons from crystal surfaces, I'd like to generate a simple "muffin-tin potential"...
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1answer
85 views

How better is PAW available in VASP when compared to that present in PS Library?

Papers with DFT calculations that use VASP work with PAW pseudopotentials which are also available in PS Library. I assume they are different since VASP is commercial. Given that, how different are ...
3
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225 views

The projector augmented wave (PAW) method, pseudopotentials (PP), and exchange correlation functionals

Disclaimer: Assume the questioner is a novice in DFT Is PAW an improvement over the pseudopotential method? In terms of Perdew, Burke, and Ernzerhof (PBE) parameterization, what is the difference ...
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120 views

Evaluate the orbital magnetic dipole moment within the PAW sphere

In general, the orbital magnetic dipole moment operator is defined as: $$- {e\over2} \mathbf{r \times v} \tag{1}$$ $\mathbf{v=p}/m$ is true only for simple Hamiltonian like $-1/2\ \nabla^2+V$, but not ...
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What is the difference between Ultrasoft, ONCV and PAW Pseudopotentials? Which is better for a spin-orbit coupled calculation?

I am trying to do spin-orbit coupled calculations for various topological insulators. I have found papers using Quantum Espresso with ONCV pseudopotentials and papers using VASP with PAW ...
10
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2answers
419 views

Are meta-GGA functionals SCAN (and its variants) ok to use in planewave DFT with the PBE pseudopotentials?

The meta-GGA SCAN functional has been there for a while. Despite the lack of SCAN (ultrasoft/PAW) pseudopotentials, various works used it in plane-wave pseudopotential calculations with ...
15
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1answer
183 views

VASP Dielectric constants: What potential to use?

I've simulated the dielectric constants using the LEPSILON = .TRUE. tag and the PBE GPAW potentials. A collegue mentioned that for accurate results norm conserving pseudo-potentials are the way to go. ...
6
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1answer
57 views

Are there properties that can only be calculated with a given set-up?

If you do a bibliography search about the codes used in matter modeling, you will find a large list. I played with a few of them (both free and commercial) and one of my findings is that the ...
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315 views

What are the types of pseudopotentials?

I would like to know what are the different types of pseudopotentials, the pro and cons, and what properties can/cannot be calculated with them?
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339 views

How to convert Unified Pseudopotential Format (UPF) into Ultrasoft Pseudopotential (USPP) format?

I am working on DFT code having plane wave along xy axis and bspline in z direction. For calculating the properties of TMD materials, spin orbit coupling must be included but i did not find fully ...
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How do I generate an aluminum force-field for a LAMMPS input file? [closed]

I have been assigned a project on the generation of a force-field of Al (aluminum) for a LAMMPS potential. I have no idea how to proceed and what to do next. Can anyone please let me know how should I ...
11
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1answer
62 views

How to generate relativistic pseudo-potential using Vanderbilt USPP that captures spin-orbit coupling?

I have used Vanderbilt USPP for generating a pseudopotential that does not include the spin-orbit term. But I want to have the spin-orbit coupling term included in the pseudopotential, to do ...
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1answer
200 views

Can GW-BSE quasiparticle calculations only be run on norm-conserving pseudopotentials (NCPPs)? If so, why not?

I've read in some texts that GW-BSE quasiparticle calculations have only been implemented on Norm-conserving Pseudopotentials (and not Ultra-soft or PAW PPs). Is there a conceptual reason for this? I ...
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488 views

Understanding the GTH Pseudopotential

I'm new to DFT. I want to make use of the GTH pseudopotential. I am trying to understand how this potential works. I read the article "Separable dual-space Gaussian pseudopotentials" by S. Goedecker, ...
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212 views

Norm-Conserving or Ultrasoft, which pseudopotential to choose?

Ultrasoft pseudopotential (USPP), in general, requires a lower energy-cutoff to the plane waves when compared to Norm-Conserving ones (NC). On the other hand (at least with Quantum ESPRESSO) the ...
8
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1answer
87 views

How to generate a pseudopotential for a cation/anion?

Many DFT codes use pseudopotentials to represent the electron-ion interaction (as do most plane-wave codes and in contrast to so-called "all-electron" programs). There are several resources on the ...
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141 views

When do relativistic effects need to be explicitly included?

For many applications with heavy metals, pseudopotentials can be used to include some amount of relativistic effects. But for what sort of systems does it become necessary to actually use a ...