Unanswered Questions
77 questions with no upvoted or accepted answers
22
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0
answers
248
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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 ...
- 15.9k
11
votes
0
answers
145
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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 ...
8
votes
0
answers
96
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How do I identify an oblique surface mesh?
I have drawn three surface meshes from a hexagonal material for the $(0001)$, $(1\bar{1}00)$ and $(1\bar{1}01)$.
The first one would be the top horizontal surface of the hexagonal structure, the ...
- 15.9k
7
votes
0
answers
57
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Database (or table) of functions obeying symmetry properties of space groups
I'm looking for a table or database containing mathematical functions that belong to crystallographic space groups by having the same symmetry elements.
Imagine a 2D square planar lattice. It has a 4-...
7
votes
0
answers
448
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Straightforward formalism to get sets of lattice vectors of fcc (111), (110) and (100) facet surfaces that I can also cite?
I am simulating low energy electron diffraction (LEED) from a polyfaceted sample. Usually it's a single, well-defined flat crystalline surface.
Since low energy electrons (below a few hundred eV) only ...
- 2,074
7
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0
answers
201
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How to convert lab frame quaternions and plane normal to misorientation quaternion and crystal plane normal for grain boundaries?
Background
Let qA and qB represent unit, orientation quaternions of grain A and grain B of a grain boundary in the lab reference ...
- 15.9k
6
votes
0
answers
83
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Practical example geometry optimization
It is common in electronic structure calculations to perform geometry optimization, which is usually posed as a (numerical) optimization problem. The atom positions are updated using, e.g., gradient ...
- 101
6
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0
answers
70
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Updated book/chapter or review article with broad perspective on computational chemistry
I really like Frank Jensen's "Introduction to Computational Chemistry" because it provides a broad perspective, starting from first principles and extending to surveys of current methods for ...
5
votes
0
answers
90
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What kind of simulation should I run to find out the temperature at which a crystal would melt?
I have learned some basics as far as performing molecular dynamics simulations, but struggle to figure out big-picture issues.
I would like to know if it's possible to find out the temperature at ...
5
votes
0
answers
41
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Rich editing of ASE images
I want to produce some images related to graphene-like materials.
I was able to draw them using ASE visualize module after constructing the atomistic model. However ...
- 24.2k
5
votes
0
answers
39
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How can calculate length or coordinate of any molecule in different quantum state [like (rotational quantum state)j=2] with any software or code?
How can one determine the bond length of a diatomic or tri-atomic molecule(rot. state J=3 and vib. state v=2) from its ground state bond length (x angstrom) using computational tools or programming ...
- 617
5
votes
0
answers
107
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What do Negative Atomic Orbital Contributions in a Mulliken Population Analysis mean?
I am performing a Mulliken population analysis (MPA) for a molecular system of interest (calculated with B3LYP/Def2-TZVP). I am analyzing the LCAO-MO coefficients/contributions associated with each &...
- 367
5
votes
0
answers
396
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How can I properly plot this .cube file in Python?
Motivation for Post: I saw a question about how to plot a .cube file recently on the Mathematica & Wolfram Language Stack Exchange. It was marked "off-...
- 143
5
votes
0
answers
47
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How to transform a perturbed surface structure to a reference surface structure?
Say I have a bulk FCC Pt structure obtained from Materials Project with a lattice constant a = 3.94 Å. I first did DFT to relax the bulk structure, and the optimized lattice constant becomes for ...
- 1,970
5
votes
0
answers
162
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Actual calculation of Coulomb energy in DFT softwares
I have a question about the actual calculation of classical Coulomb interaction term in density functional theory (DFT) softwares.
Of course I understand the form Coulomb energy as:
$\int\int \frac{\...
- 1,799