Unanswered Questions

205 questions with no upvoted or accepted answers
27
votes
0answers
276 views

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 ...
20
votes
0answers
272 views

What are the tools available for point defects calculations?

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? It would be appreciated if you could explain one of ...
17
votes
0answers
123 views

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 ...
15
votes
0answers
129 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^\...
14
votes
0answers
139 views

Empirically determining thermostat damping factor

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, tracking ...
13
votes
0answers
148 views

CP2K vs BigDFT comparison

I typically run DFT calculations with 1000 to 5000 atoms using CP2K. This works fine but I'm interested in BigDFT also. Is there anyone here that has experience using BigDFT and is able to compare ...
13
votes
0answers
91 views
13
votes
0answers
165 views

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 ...
12
votes
0answers
98 views

What are the recent developments of GW@BSE to simulate the excited properties of materials?

A twin question related to the TDDFT method is asked in another post. But any comparisons between both methods in recent developments are welcome. The time-dependent density functional theory (TDDFT) ...
12
votes
0answers
121 views

How do I know if the reconstruction in the picture is a 2x2 reconstruction?

How do I know if the reconstruction in the picture is a 2x2 reconstruction or not?                                     I believe that this corresponds to a 2x2 reconstruction because there's an even ...
12
votes
0answers
168 views

First order variation of the wave function of conduction states

The first order variation of the wave function $\Delta \psi_n$ is obtained by standard perturbation theory (Eq. 25 of ref 1): \begin{equation} (H_{SCF}-\epsilon_n)|\Delta \psi_n \rangle = -(\Delta V_{...
11
votes
0answers
80 views

Looking for crystal generator library

I am looking for a C or a C++ library that can do crystal generation, that is, multiply unit cells in one or more directions with symmetry information. (in other words, generate supercells). I have ...
11
votes
0answers
91 views

What are good protocols for creating a database based on python?

I am aware of software tools such as atomate, but that is quite specific to crystals. There are other equally specific workflows - I think we all have our own... What I am interested in is making my ...
11
votes
0answers
60 views

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 ...
11
votes
0answers
123 views

Inconsistent data of chemical potential from different papers

I am looking for chemical potential from literature.$^{1,2}$ I compared the method and data they provided. They use the Fitted Elemental Reference Energy method via GGA+U on VASP employing PAW. U ...

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