Unanswered Questions

67 questions with no upvoted or accepted answers
24
votes
0answers
121 views

In which paper, or at which point in time, did this cross-pollination between the fields of Operations Research and Materials Modeling begin?

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 ...
19
votes
0answers
118 views

What are the best functionals for transition metal compounds?

Some properties of transition metal compounds can be influenced by static correlation, relativistic effects, and, in some cases, close-lying electronic states could result in difficulties in SCF ...
17
votes
0answers
49 views

What is the importance of electron interaction on dielectric response of crystals?

After obtaining the Kohn-Sham orbitals from a plane-wave-based self-consistent-field calculation, the dipole matrix elements could be calculated in order to determine electro-optical properties such ...
17
votes
0answers
77 views

Which dispersion corrections in DFT exist, and how do they compare?

There are many different dispersion corrections out there. The most famous is D3 [1] (and the new D4 [2]), but there is also the so-called vdW kernel [3], and probably other approaches. The question ...
16
votes
0answers
45 views

What class of materials are closest to realizing the tunable coupling Hamiltonian?

From a physics point of view, there is an effective (approximation to second-order coupling Jaynes-Cummings) Hamiltonian of the form [1] \begin{equation} \tilde{H}=\sum_j\tilde{\omega}_j\sigma_j^z+\...
15
votes
0answers
48 views

Cancellation of Errors in density functional approximations or any wavefunction based methods

I am curious to find references for when is it TRUE that the error cancellation in approximate methods like DFT/MP2/etc. are valid and when they fall apart. For example: My understanding is (please ...
15
votes
0answers
60 views

What is the difference between BDFT and CDFT (magnetic-field DFT and current DFT)?

Following the previous discussion on DFT in strong fields, I would like to ask about the difference between those two alternatives (BDFT and CDFT). By CDFT I do not mean (constrained DFT, but current ...
15
votes
0answers
42 views

QMC calculation of the equation of state of metals

Is diffusion/variational quantum Monte Carlo applicable to the calculation of the athermal (zero temperature, no zero point energy) equation of state of metals including electronic correlation? For ...
15
votes
0answers
53 views

What is the current status of active learning methods in atomistic machine learning?

Many machine learning attempts in atomistic applications (see this answer) seem to parameterize models on calculated data (i.e., CCSD(T), DFT, etc.). This approach suggests some automatic procedure ...
14
votes
0answers
54 views

Benchmarking data for Ewald summation algorithms

Are there good benchmarks available for testing homemade Ewald summation code? Optimally it would be very nice if there was several types of systems. NIST has a very nice benchmark for energies of ...
14
votes
0answers
43 views

How trustworthy is the Tran-Blaha modified Becke-Johnson potential and how does it perform across basis sets?

When modeling solid-state materials and particularly semiconductors, one must go beyond LDA and GGA. One alternative is to use hybrid functionals or the $GW$ method. However, this can be very ...
14
votes
0answers
57 views

Where is there a list of all universality classes for phase transitions with examples of each?

I've often has this problem: I have a model that has a phase transition in it, but I don't know what universality class it falls into or what the universality class is called. Is there anywhere on ...
13
votes
0answers
64 views

Understanding the GTH Pseudopotential

I'm new to DFT. I want to make use of the GTH pseudopotential. I am trying to understand how this potential works. I read the article "Separable dual-space Gaussian pseudopotentials" by S. Goedecker, ...
13
votes
0answers
46 views

Hexagonal lattice volume EOS fit

I have a little problem concerning hexagonal volume fitting using VASP. I have followed these steps: Relax the structure from a given volume using ISIF =4 Copy ...
13
votes
0answers
40 views

Which basis set families were optimized to give the lowest possible variational energy for a given number of orbitals?

Dunning's basis set families (such as cc-pVXZ and aug-cc-pCVXZ) were not optimized to give the lowest variational energy for a given number of orbitals. For example the S-type orbitals are optimized, ...

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