Unanswered Questions

69 questions with no upvoted or accepted answers
16
votes
0answers
78 views

Quadrature over three Euler Angles for orientation averaging

Does anybody know about an accurate quadrature rule over three Euler angles $\theta, \phi, \chi$? I am trying to calculate the average value of an arbitrary function $f(\theta, \phi, \chi)$ for a ...
15
votes
0answers
91 views

How to calculate t-zero temperature using Thermo-Calc- Python (TCPython) for multiple alloys?

T-zero temperature is the temperature at which the Gibbs energies of two phases are equal. Here, I wish to find the temperature at which FCC and BCC have same Gibbs energy. Thermo-Calc console mode ...
14
votes
0answers
36 views

Benchmark Timings of Machine Learning Potentials vs Molecular Mechanics Force Fields

Machine learning is an increasingly common tool for developing force fields for molecular dynamics simulations. It's not totally clear what should be considered a machine-learning potential, but let's ...
14
votes
0answers
57 views

Converging the potential of a dilute binary alloy system using the Coherent Potential Approximation. What troubleshooting options could I take?

I'm trying to converge a dilute fcc alloy consisting of Cu and U, with the Uranium concentration at 0.01% and the lattice parameter of Cu, using Hubert Ebert's Spin Polarized Relativistic Korringa-...
14
votes
0answers
119 views

How to set up a local server for iQmol on macOS?

I'm trying to set up iQmol as a tool to submit calculations to Q-Chem on our lab machines to make access to it easier for OChem students. Unfortunately, it is not working properly "from the box&...
14
votes
0answers
58 views

How to find the projected Hamiltonian for lowest flat-band in general?

In [1], starting with the bosonic Hamiltonian (Eqn. 1) for the dice lattice model with half flux density (with Ahronov-Bohm phases incorporated), \begin{equation} H=-t\sum_{\langle j,\mu\rangle}(a^\...
13
votes
0answers
82 views

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 ...
13
votes
0answers
130 views

What kind of information can be extracted from alloy microstructure images converted to Fourier space?

I have some alloy microstructure images, showing elongated grains (darker colours) and the grain boundaries (lighter colours). If I take the Fourier transform of the image, there are directional bands ...
11
votes
0answers
44 views

Empirically determining thermostat damping factor

tl;dr Is there a way to determine an appropriate thermostat damping factor given a timestep size and a numerical integration method? I am computing a set of simulations in LAMMPS, using ReaxFF, ...
11
votes
0answers
103 views

Is there a software for macOS that can calculate collision cross-sections involving molecules with several atoms?

What macOS software currently can be accessibly used to calculate collision cross section using the geometries obtained from DFT? In my case, Q-Chem is used for geometry optimization. The goal is to ...
11
votes
0answers
56 views

What are the advantages of different point defects calculation tools?

As far as I know, there are mainly PyCDT, PyDEF, pylada and some part of pymatgen. As a new user to those tools, which one would be a good choice? pycdt: Python Charge Defects Toolkit (PyCDT) is a ...
11
votes
0answers
182 views

How to understand dynamical spin structure factor?

A newish area of interactions between quantum Monte Carlo (QMC) and experiments is in spin spectra. Recent improvements in stochastic analytic continuation have made it much easier to compare/extract ...
10
votes
0answers
31 views

How exactly does one compute the vibrational density of states from the output of a molecular dynamics simulation?

There are many things that can be done with the output of a molecular dynamics simulation, but one of the more powerful things is the ability to compute the vibrational density of states (or the ...
9
votes
0answers
58 views

Is there a software that has implemented forces of TDDFT calculations for solids?

I'd like to investigate the structural relaxations of the excited state for periodic systems. BSE and TDDFT are two promising methods for this purpose. While there is a discussion on BSE Is there a ...
9
votes
0answers
48 views

Correcting thermodynamic data for concentration, what concentration is best to use?

In computational chemistry when using transition state theory we often use standard states for all involved structures. However, sometimes people argue that it should be corrected for concentration (...

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