All Questions

I am studying pairwise-additive systems in statistical mechanics. These are systems with particles which only have a 2-body potential defined. When trying to find the pressure of such a system, we do $...

This question is related to this paper: J. Phys. Chem. Lett. 2017, 8, 13, 2999–3007 The above figure shows symmetry analysis for the band structure. The author writes: The band symmetry and parity ...

In order to model an interstitial trapped in a metal lattice, and the associated incorporation energy, which should be used - "relax" or "vc-relax"? I want to understand the ...

Suppose I have a functioning molecular dynamics package for classical MD. I want to extend this code to run path integral MD. I know that a surprisingly small number of new features need to be ...

I'm trying to make a pipeline geometry optimization -> calculation of polarizability/hyperpolarizability. And NWChem seems pretty good for it, the only thing I can't understand its how to calculate ...

I'm trying to reconstruct the surface $(1\bar{1}01)$ in an hexagonal material and the reconstruction is described by the matrix $\begin{pmatrix} \hspace{3mm}3 \hspace{2mm}1 \\-1 \hspace{2mm}2 \end{...

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 ...

I have drawn three surface meshes from a hexagonal material for the $(0001)$, $(1\bar{1}00)$ and $(1\bar{1}01)$ . The first one would be the top horizontal surface of the hexagonal structure, the ...

I have been using cif2cell for converting CIF files into quantum ESPRESSO input files. But cif2cell always keeps the ibrav value to be zero and indicates the CELL_PARAMETERS. As per the quantum ...

What sources would you recommend (or if you could instead explain it to me that would be great). I have never studied crystallography but must do a module on it and in some of the questions we were ...

I have known some kinds of stability of materials, such as: Mechanical stability; Dynamical stability; Thermal stability In particular, they can be studied with first-principles computational ...

If I am using Quantum ESPRESSO for my work, how can I know the number of CPUs necessary for a certain DFT calculation?

I have to calculate the elastic constants of a Cubic system using a Density functional theory-based software. A cubic system will be mechanically stable if it satisfies the Born-stability condition (...

I have two brakets (the angular momentum matrix elements) that are $$ \langle \partial_\mathbf{k} \psi_{n \mathbf{k}} | \times \mathbf{p} | \psi_{m \mathbf{k}} \rangle \tag{1} $$ $$ \langle \psi_{n \...

Assuming I have an experimental powder XRD spectra and I have a number of computational structures without any knowledge of which is correct, how can I simulate the powder XRD spectra? Once I have ...

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 ...

Recently I am trying to calculate the BSE and IQP transition dipole based on VASP lecture on BSE and BSE fatband. However, I have a few questions regarding the BSE and IQP oscillator strength. From ...

Recently, I learnt that basis sets can be contracted as segmented (like def2 or 6-31G) or general (like cc-PVTZ, or ANO). The general contraction allows all the primitives to appear in all shells, ...

I can't seem to articulate what made me ask this question but it sprang up when I asked: What does it mean to say a material is 'anharmonic'?. I've heard before that the electronic entropy ...

I understand that a harmonic picture of the potential in a material isn't enough to study lattice dynamics thoroughly. The quasi-harmonic approximation is a good workaround and helps incorporate ...

This question is coming from an answer to one of my previous questions. During optimizations, QM programs usually compute the gradient(first derivative) analytically, and take a guess of the hessian (...

Even though it is a powerful tool, Quantum ESPRESSO's hardware requirements are very high. For instance, to evaluate optical properties, even for structures with tens of atoms, Quantum ESPRESSO can ...

I know that it is possible to get order constitution data for phases when using Thermo-Calc's GUI (e.g. to get "BCC_B2 DISORD" instead of just "BCC_B2") for a single equilibrium ...

What are some of the biggest open-questions / challenges in Condensed Phase theory and computation? What efforts are being done to answer them? I realize Condensed Phase chemistry is a huge field, but ...

I am trying to run spin polarised DFT calculation in Quantum ESPRESSO on system Co2MnSi. I kept starting magnetization for all these three species as, ...

I am calculating MSDs for the first time and have been struggling to find newbie-level resources on understanding them. If anyone could please suggest any resources or provide guidance on how to ...

I have a mechanism where two parts are screwed and unscrewed and I wish to incorporate a system by which the number of screwing and unscrewing can be indicated. I have thought of a method using the ...

I have been working with an anti-ferromagnetic material Cobalt Oxide. And in the image given below the blue spheres are Co ions. The blue spheres form a tetrahedron shape. And I've assigned the spin ...

The theory of elasticity is essential in engineering. The most basic law is that any piece becomes smaller if one compresses it. My question is: How can a piece of material expand (some minutes, hours,...

I want to know how to make 2D Quantum dots in Vesta?

Should I take MOF (metal-organic framework) as a periodic structure or an isolated cluster? What's the difference between them? If it's periodic, can I do an analysis of the electronic structure, such ...

For bulk and two-dimensional materials, we can download the structures from many databases, such as Materials Project and CMR. Are there also similar databases for MOF (metal-organic framework) ...

I've been trying to run a Thermo-Calc one axis equilibrium calculation on some quaternary alloys in the TCHEA4 database. Most of the calculations work fine, but for some alloys it gets stuck in a loop ...

I want to study the properties of metal-organic framework (MOF) materials with DFT implemented in VASP. What's the pitfall for this kind of simulation? Which points should I take special care of? I ...

I wonder whether or not it would be useful to design and construct a double-sided Whiteboard (i.e. the front and back sides can both be used)? The cost of the Whiteboard product would increase, but ...

I have been having trouble with the VIBRATIONAL_ANALYSIS routine. Namely, the routine keeps timing out. I am trying to find the vibrational modes of Pyridine in a non periodic system, as well as Mo2C ...

Preparing good figures is an important part of reporting molecular modeling results. There are many programs that can be used to visualize and generate images from all sorts of programs and approaches....

I notice that most codes can only perform finite difference calculations when including van der Waals interaction. Are there any codes that can apply density functional perturbation theory (DFPT) in ...

This question is inspired by this post. In the Kohn-Sham framework of density functional theory, the total energy is expressed as: $$E=E_{kin}^{non}+E_{ext}+E_{H}+E_{xc}$$ in which The first term is ...

This question might seem more suited for the Physics SE but I'm asking it here because of its many applications in materials modelling. Lattice dynamics codes like ...

I want to study the effect of nitrogen interstitials on oxygen diffusion in metals and vice-versa. Would you suggest MSD calculations in LAMMPS to be a viable method for this? There aren't many ...

How can I simulate the work function given by Ultraviolet Photoelectron Spectrum (UPS) of a molecule or a molecular crystal? I thought it is an easy job: Just do a geometry optimization and get the ...

I am revisiting some exercises in Thijssen's Computational Physics book, particularly chapter 4 on the Hartree-Fock method. I am interested in the method of nonlinear optimisation for its own purposes,...

Sorry if this question is too simple for the community but I really could not find an explanation. A detailed answer would be appreciated.

I was able to calculate band energies in quantum espresso. How to convert them to values that are in terms of difference from vacuum energy?

I have tried to simulate the hysteresis loop for the exchange spring structure using Mumax3. I have already simulated the hysteresis loop for the conventional bilayer soft-hard structure. Please find ...

What is the best python package to construct Smooth Overlap of Atomic Positions (SOAP) descriptors given SMILES representation of a molecule? Is this even possible without providing 3D geometry? An ...

I am a beginner user of Pymatgen package. In order to process the data from VASP DFT calculation software, I use Pymatgen to visualise the output band structure. When I do spin polarised band ...

I have used a few codes for studying magnetic materials (specifically core-shell nanoparticles with an AFM shell and an FM core). These are: Vampire: For the calculation of curie temperature via ...

The following figure is the electron localization function (ELF) for monolayer LaBr$_2$. The ELF is calculated to reflect the bonding character in SL LaBr$_2$. As shown in the figure, ELF shows two ...