# Matter Modeling Stack Exchange Community Digest

## Top new questions this week:

### How to determine which levels correspond to each other in LS coupling and jj-coupling?

In the LS coupling scheme, L, S and J are good quantum numbers; whereas in jj-coupling scheme, j1, j2 and J are good quantum numbers. I have learnt how to get the term symbols for LS coupling, and for ...

quantum-mechanics spectroscopy spin-orbit-coupling from-chem-se atomic-physics

### Functional group detection from geometry

I am currently looking for an efficient way to detect common functional groups - that is, characterize whether a molecule is an alcohol, an aromatic compound, etc. - in a larger database consisting of ...

software molecular-modeling geometry

### Proper handling of change of units in numerical calculations

Let's say I want to calculate the energy spectrum of Heisenberg model: $H = J \sum \limits_{\langle i,j \rangle} \vec S_i \cdot \vec S_j -g ~\mu_B \sum \limits_{i} \vec S_i \cdot \vec B$ but value of ...

model-hamiltonians

### What do we mean by spin-splitting energy?

What is the meaning of spin-splitting energy as described here?

density-of-states transition-metals spin crystal-field

### What is the meaning of element-rich environment in calculating formation energy?

I want to use the formation energy formula used by the article in the picture below. The authors have used the term S or Sn-rich environment. What is the meaning of ...

density-functional-theory

### How to make a python code that can read a .xyz file and find distance between atoms?

I want to make a python script that will load an xyz file. From the xyz parameters, I need to find the distance between atoms, angle and dihedral between atoms. The file xyz have this structure: ...

crystal-structure python geometry programming software-online-tools

### How to calculate the volumetric energy density of a molecule?

I am trying to store hydrogen in a hydrocarbon. The example can be taken as cyclohexane ($\ce{C6H12}$) which is in a hydrogen-rich state. Its hydrogen-lean state is Benzene. I want to calculate the ...

molecular-dynamics molecular-modeling physical-properties-of-materials experimental

## Greatest hits from previous weeks:

### How does the recent Chinese quantum supremacy claim compare with Google's?

Very recently, China claims achieving 'Quantum Supremacy' with the world's fastest Quantum Computer. Their computer was designed as a circuit of lasers, beam splitters and mirrors (see figure bellow) ...

high-performance-computing quantum-computing

### Is there a free package with robust CASSCF functionality?

Among free software packages, which one has robust CASSCF functionality? The FCI solver can be implemented in either way, e.g., direct solver, DMRG, etc.

### Density of States of Supercells

Are there any important considerations to make for density of state calculations for supercells? With band structures typically band unfolding schemes make things easier to understand but is there ...

band-structure density-of-states castep

### Is the number of possible Bravais lattices a mathematical fact?

Almost anyone that has taken a Solid State Physics course will know, that any 3D crystal must be in one of the 14 Bravais lattices due to symmetry operations and space filling. In 2015, a paper was ...

crystal-structure crystallography symmetry

### 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 ...

density-functional-theory software vasp
 answered by Chi Kou 1 vote

### Is it better for me to study chemistry or physics?

I might decide to pursue material science. Aptitude and background I am from the UK, and for A-levels, I am studying Maths, Further Maths, Physics and Chemistry, and I am predicted decent grades in ...

### What does "level of theory" mean?

I was reading this paper on the QM9 synthetic molecular database and their computed properties. It is stated that All properties were calculated at the B3LYP/6-31G(2df,p) level of quantum chemistry. ...

quantum-chemistry

## Can you answer these questions?

### When import volumetric data ( spin density of CHGCAR) to VESTA which option should we pick here?

I am trying to plot SPIN DENSITY isosurfaces using VESTA. I have used vaspkit option 312 to create ...

density-functional-theory vasp vesta

### Read a data file into the atoms object in ASE

There isn't that many tutorials on Atomic Simulation Environment on the net and among those I saw, the atoms object is always built explicitly within Python. What if I have a data file containing the ...

atomic-simulation-environment software-usage