Unanswered Questions
424 questions with no upvoted or accepted answers
32
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0
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418
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Where/when did the fields of Operations Research and Spin Physics or Molecular Dynamics begin to cross-pollinate?
Operations Research is a field of mathematics in which optimal or near-optimal solutions are sought for complicated problems.
In the modeling of materials, we often optimize Ising models, in which the ...
- 15k
19
votes
0
answers
194
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What are the recent developments of TDDFT to simulate the excited properties of materials?
The time-dependent density functional theory (TDDFT) and the many-body perturbation method (GW@BSE) are considered as the two most popular and successful methods to describe the excited-stated ...
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18
votes
0
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862
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Interpreting electron localization function (ELF) results
Studying the interaction of a boron-nitride nanostructure with lead, we calculated the wave function using Gaussian software (single point energy with basis-set mix 6-311G++/lanl2dz and hseh1pbe ...
- 15k
18
votes
0
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210
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Is there a software that can do derivatives with respect to user defined vibrational modes?
I'm doing some property calculations that depend on a sum of derivatives of some quantity with respect to normal vibrational modes. I was hoping to find some physical intuition relating the type of ...
- 15k
15
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238
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Why does the Wolff algorithm slow down in a 4-body Ising model?
In the paper that introduced "Self-learning MC" (an ML-inspired MC technique, as I understand) the authors consider a many-body Ising model as an example to show the efficiency of their ...
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13
votes
0
answers
395
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Applicability of GFN-FF force field and other xTB methods for dynamics of ions in water
I am working on a project involving water clusters with ions in them. One of the problems that I ran into quite early on was that good forcefield parameters are not available for highly charged ions ...
- 101
13
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0
answers
274
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Calculating the Chern number on a 2D surface of a 3D insulator
I want to calculate the Chern number of a surface of 3D time reversal insulator. I know the 3D topological insulator is characterized by the Z2 index annd that the Chern number can be used to ...
- 15k
13
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0
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566
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How to build amorphous Al2O3 using the AIMD method implemented in VASP?
I want to build amorphous $\ce{Al_2O_3}$ with the AIMD (ab initio molecular dynamics) method implemented in VASP.
I'm thinking of this process in three steps:
Build initial supercell
Melt
Quench
I ...
- 33.1k
12
votes
0
answers
220
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Orbital magnetization in periodic solids
The orbital magnetization in periodic solids has been nicely described by the so-called modern theory of magnetization [1,2,3,4].
$$\tag{1}
\mathcal{M}_{orb} = -\frac{1}{2} \Im \sum_{n,\mathbf{k}} f_{...
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12
votes
0
answers
92
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A viscoelastic material with nonconvex memory kernel?
The title is basically my question. Viscoelastic materials are characterized by a constitutive equation between stress and strain involving a convolution integral. This integral is weighted with a ...
- 33.1k
11
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210
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Calculating Core-Level Binding Energies (XPS) using DFT
I'm pretty new to DFT calculations but I'm trying to learn how to do X-ray photoelectron spectroscopy (XPS) calculations, particularly for open-shell molecular systems in common non-periodic DFT codes....
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10
votes
0
answers
115
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Is it possible to calculate non-resonant Raman coefficient in Quantum ESPRESSO for systems that require smearing to converge?
In Quantum ESPRESSO turning lraman to true in the ph.x input is not possible if the material is made to converge using smearing. Is there any way to circumvent this, as my material isn't a metallic a ...
- 33.1k
10
votes
0
answers
119
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Handling multiple self-consistent solutions with DFT+U
It is well-established that within the DFT+U framework, one can achieve several self-consistent solutions with greatly varying energies for the same exact magnetic ordering. In 2010, Meredig et al. ...
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10
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0
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199
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How to plot the electrostatic potential calculated with XTB?
Following this question, I am interested now in plotting the electrostatic potential as calculated with the XTB program.
I found how to set up the calculation but as a result, I got three files that I ...
9
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0
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112
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Have FDTD methods made inroads into dynamical simulation of electron and/or X-ray scattering by crystals?
I'm afraid this question might be too basic or too naive or both, but here goes!
For optical diffraction by periodic nano-structures (gratings, semiconductor manufacturing metrology) the rigorous ...
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