Questions tagged [symmetry]
Questions relating to symmetries and symmetry groups encountered in materials modeling.
12
questions with no upvoted or accepted answers
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Is the formula of a Dyson orbital independent of whether there is degeneracy or not in the HOMO of the neutral?
A Dyson orbital is defined as:
$$
\textrm{Dy}(x) = \int dx_1 \ldots dx_{N-1} \, (\Psi^+(x_1,\ldots,x_{N-1}))^* \, \Psi^0(x_1,\ldots,x_{N-1}, x),\tag{1}
$$
where $\Psi^0$ and $\Psi^+$ are the total ...
- 605
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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-...
- 141
5
votes
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46
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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
4
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41
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How can we identify the symmetry of the molecule from its IC table?
We are given the IC table for benzene in CHARMM format, which can be written as follows:
...
- 4,036
4
votes
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How to Obtain the Zak Phase in Symmetric one-dimensional (1D) Systems?
In a symmetric 1D system, the intrinsic topological orders are characterized by the total Zak phase ($\gamma$) summed over all occupied states$$\tag{1}\gamma=\sum_{n}^{}\gamma_n$$where $n$ is the band ...
- 3,535
4
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105
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Why are some point groups for single atoms listed as Oh in the CCCBDB?
Does anyone know why the CCCBDB database lists the tin cation and antimony atom as having the Oh point group (please see the screenshot below from CCCBDB when I look at "All molecules sorted by ...
- 133
4
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201
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If the system respects time-reversal symmetry, does the T-even anti-symmetric conductivity tensor indicate a dissipationless transport?
In this paper, the authors discuss the three response relations or Ohm's law for spin/charge transport. The first one is the spin Hall effect described by:
$$J_j^i=\sigma_{s}\epsilon_{ijk}E_k \tag{1},$...
- 15.3k
3
votes
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35
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Calculating degrees of freedom with fixed symmetry
I stumbled upon a problem recently: I want to compute the number of degrees of freedom for a crystal/molecule if its symmetry is fixed.
I think what needs to be done is to compute the number of normal ...
- 1,437
3
votes
0
answers
390
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How to transform the conventional cell to primitive cell, by hand?
I am following this tutorial to transform a conventional cell to a primitive cell, but I am not sure how to determine the primitive copy of some atom in the conventional cell.
For example, in the ...
- 2,087
2
votes
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49
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How to force which degenerate orbital is occupied during the HF optimization process on Gaussian09?
I am currently running a RHF calculation on a singlet fragment of the central atom in a $D_{2h}$ symmetric linear molecule contained in the $z$-axis (both the $x$- and $y$-axes are degenerate). The ...
- 367
2
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98
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Help setting the input geometry into standard orientation for a single point g09 calculation
I am trying to run a single point g09 calculation for a pentagonal planar molecule with D5h symmetry using the B3LYP/LANL2DZ level or theory.
I would like the calculation to use symmetry, however the ...
- 367
2
votes
0
answers
137
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LO-TO Splitting and Group Theory
I am curious whether or not there is a connection between the group theoretical assignment of phonon modes and LO-TO splitting. For example, is it true that the frequency of a gerade mode will depend ...
- 373