Unanswered Questions

236 questions with no upvoted or accepted answers
28 votes
0 answers
325 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 ...
19 votes
0 answers
140 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 ...
18 votes
0 answers
169 views

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 votes
0 answers
90 views

Constructing a molecular polarizability tensor from sets of atomic polarizabilities?

Often empirical electrostatic models or molecular force fields approximate the molecular polarizability using an additive model, e.g., for N atoms: $$ \alpha_{mol} = \sum_i^N \alpha_{atom_i} $$ This ...
15 votes
0 answers
203 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 ...
15 votes
0 answers
416 views

Interpreting electron localization function (ELF) results

Studying the interaction of a boron-nitride nanostructure with lead, we calculated the wave function using Gaussian software (single point energy with basis-set mix 6-311G++/lanl2dz and hseh1pbe ...
15 votes
0 answers
137 views

What are the ways to add dynamic correlation to an MCSCF wavefunction?

We recently learned about the many types of MCSCF, which treat "static" electron correlation. There are then many ways to treat further "dynamic" electron correlation to try and ...
14 votes
0 answers
125 views

How to differentiate similar clusters in the mcsqs output in ATAT?

Consider the following bestcorr.out file: ...
13 votes
0 answers
121 views

Is there an example in which TD-DFT was successful in describing photophysical or photochemical processes?

Time-dependent Density Functional Theory has been around for quite a while now, seeing Density-Functional Theory for Time-Dependent Systems, and so it has been developed extensively, implemented in ...
13 votes
0 answers
113 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
0 answers
69 views

Easy ways to generate "teaching" band structures in Python?

I'd like to introduce band structure to a class of undergraduate chemists, along the lines of Roald Hoffmann's Solids and Surfaces. That is, I'd like to start with a 1D s-band - which is easy because ...
12 votes
0 answers
137 views

How may I calculate the "effective transfer integral" in free electronic-structure software?

I would like to calculate the following four quantities in a free electronic structure program: \begin{alignat}{2}\tag{1} e_1&=\langle\phi_1|H^{KS}|\phi_1\rangle,\\ e_2&=\langle\phi_2|H^{KS}|\...
12 votes
0 answers
199 views

How to calculate RDFs for MD trajectories without PBC, directly from coordinates?

I have been running MD simulations on water droplets with an ion in them. I am trying to implement a program that could calculate the radial distribution function from ion to oxygen (or ion to ...
12 votes
0 answers
136 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 ...
12 votes
0 answers
145 views

Calculating the Chern number on a 2D surface of a 3D insulator

I want to calculate the Chern number of a surface of 3D time reversal insulator. I know the 3D topological insulator is characterized by the Z2 index annd that the Chern number can be used to ...

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