All Questions

I want to learn DFT for research purposes and I need to implement a toy DFT for pedagogical reasons. I would like some recommendations regarding resources like books, articles, or any other thing that ...

Electron-phonon coupling, and more generally electron-ion coupling, is highly important for all sorts of things from superconductivity to heat transport and thermoelectrics. Computationally, there are ...

After calculating the band diagram of a structure, is there a way to identify localized surface states? I am working with Si nanowires with different cross sections. I want to determine the band gap ...

I have the following molecule in SMILE format (saved as my_molecule.smi): ...

I am currently working on prediction of UV-vis spectra from structure of molecules. I have read multiple papers where structure descriptors were used as inputs for machine learning to find various ...

While calculating the band structure using VASP, we usually take two steps: one is about self-consistent run to get the right CHGCAR file; and the other is about non self-consistent calculation ...

Is there a way to search to search for specific structural motifs in proteins? For example can a database where we can find structures with zing finger motif or an hairpin... PDBeMotif (ebi.ac.uk) has ...

Is the following notation $\Phi^\mathrm{HF}_0 \equiv | \phi_1, \phi_2, \cdots, \phi_i, \phi_j, \cdots, \phi_N \rangle$ $\Phi_{ia} \equiv | \phi_1, \phi_2, \cdots, \phi_a, \phi_j, \cdots, \phi_N \...

I am stuck in calculating the frequencies of one optimised geometry for naphthalene CASSCF(10,10) with Gaussian 16. I have optimised its geometry and checked the active space is the pi system of it, ...

Does PySCF support CAS-SCF calculations? If not, it is possible to implement it based on their GTO integral library?

I have run a HF calculation on naphthalene and I have checked the MOs that have been obtained. Now, I have to select my active and inactive orbitals for CASCF(10,10). As there are 34 occupied orbitals,...

I am working on $\ce{GeHfTe}$ and in the case of a non-collinear calculation, I am getting the DOS in the attached photo. I have already relaxed my structure with VC-relax and it is converged with ...

When you submit a paper to be published, the journal will ask you to suggest at least three reviewers. My question is how to search for appropriate reviewers for your paper?

I have one doubt about K points selection for a supercell. I construct one 2X2X1 supercell with 64 atoms having a=11.19, b=11.19, c=5.59. For checking K points convergence test with energy should I ...

I am running a simple example of vc-relax/scf for aluminum using PBE pseudo-potential.Setting are given below ...

What does the following notation mean? $$A_{20}\left<r^2\right> = -100 \mathrm{K}$$ Where $A_{20}$ is termed a Crystal Electric Field Parameter. I often see this notation when reading papers on ...

We are all aware of the fact that MD Simulations using force fields can treat very big systems. But they cannot handle "exotic" materials. Why?

I am running an ONIOM optimization calculation on GAUSSIAN software and when I open the LOG file I get a warnig saying: ...

How to run hp.x command in QuantumEspresso v6.8? It is saying command not found. After doing ...

Following to this post, I would like to know how to perform linear response theory for calculation of U Hubbard parameter in VASP?

I adapted an example first-principles water simulation to do simulations of liquid SiO2, but did not know what I was doing and did not remove a Grimme dispersion correction term. It would be great to ...

I am using Quantum Espresso to simulate a platinum surface with ligands, so far everything is working ok. I now need to introduce a solvated hydronium $H_3O^+(H_2O)_2$. Is there something I should be ...

When it comes to improving the accuracy of DFT calculations, there is a well known hierarchy: starting from LDA using $E_{xc}[n]$, proceeding with GGA and its $E_{xc}[ n, \nabla n]$ dependency and ...

If I need to draw the band structure of a semiconductor, like when I do CFD simulations, I am guessing I will need a lot of k-points to form a fine mesh in the k-space, but in reality, it seems the ...

Background Quasiparticle interference (QPI) is a technique that can be used to study 2D surface state band structure; carrier reflections at boundaries or impurity sites will interfere producing ...

I was facing convergence problems in my 2D system, but after I have used the ALGO = All tag the convergence problems have gone. I would like to know how accurate is ...

I have a set of molecular dimers (~25 atoms) for which DFT-D3 interaction energies are calculated by Psi4 and Turbomole program. Now I want to compare these values against Force-Field methods like UFF/...

In computational chemistry, I have come across many test sets which are used to benchmark a new method. For example, the G2 test set for thermochemical calculations (heats of formation). There is the ...

I am going to simulate the electronic structure of the Au 111 surface including Fe-centered porphyrin on top. Since the molecule includes Fe, I first did spin-polarized calculations. Using converged ...

electronic circular dichroism (ECD) spectra is commonly used in organic chemistry to characterize chiral molecules. Here the question is how to simulate ECD spectra using MCTDH (Multi-configurational ...

I read a paper and the authors wrote they use AIMD to estimate the ionic diffusivity of materials. I wonder steps to obtain the value at different temperatures. What are the input and output of ...

I'm trying to calculate the magnetic anisotropy energy of Cr2O3 by comparing the total energy difference of the system in different spin configurations (in-plane and out-of-plane). However, when ...

Consider the following situation that the exchange-correlation term (e.g., B3LYP) overestimates the energy in a system (i.e., a simpler one (e.g., LDA) is sufficient in the system). In this case, my ...

For example, in something like the General Utility Lattice Program, you perform structural optimisation and then use phonons to calculate properties like elastic constants etc. The latter part seems ...

I found the only parameter related to pressure is Pstress tag in VASP. But the pressure of Pstress tag is Hydrostatic pressure, while I only want to put stress along z-axis. Could you please help me ...

When it comes to studying 2D, 1D or 0D nanomaterials, saturating the dangling bonds in the surface helps remove unwanted localized surface states from the band structure 1. However, so far I have not ...

In my bachelor thesis, I am trying to use the VEDA program to analyze the vibrational energy distribution to associate different vibrations to the calculated modes from gaussian. I am stuck now ...

I generated the following SQS cell using ATAT (the sructure is converted to POSCAR format) ...

Hexagonal unit cells can be converted to rhombohedral unit cells, and the latter unit cells have fewer atoms. But how can I convert them? Is there any software or codes that are able to do this ...

I have a magnetic crystal system. I want to calculate the total energy of the system if the magnetization direction is aligned in different directions such as [110], [010]. By default Quantum ESPRESSO ...

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 ...

I am using Quantum Espresso along with a different code, I am performing calculations on Platinum bulk. After choosing the "cold" smearing (which I read is a good choice for metals) with a ...

I know the title sounds opinion-based (and admitedly, part of my question is), but I will try to bring more practical elements to the question: Here is my problem: I have been testing a force field ...

I have been attempting to optimize the structure of a Si nanowire using SIESTA. The original structure fed into the optimization is as follows. Once it is optimized, the structure would change to ...

Specifically, in the General Utility Lattice Program (GULP) 2003 paper, in the methods section on Two-body Short-range Interactions we have the following: For covalently bonded atoms, it is often ...

I am trying to make plots based to VASP simulation results, but I am struggling with how to download so much data from the server. A lot of examples on the internet are taught using the local desktop ...

Can we optimize a molecular structure using Moller-Plesset MP4 method on GAUSSIAN software? If yes what keyword do we have to add?

I know there are programs that can automatically visualize .cube files (like VMD), but I'm trying to do it myself in python/matplotlib (or equivalent) to better understand what the numbers mean. I ...

When conducting a minimization on Gaussian software, What are the procedures used to eliminate imaginary frequencies if we have already found a stationary point? Are there any keywords that would help ...

In DFT calculations using vasp, symmetry analysis are performed to determine space group symmetries at first, if symmetrization is turned on, such as ISYM = 2. When magmoms are set in INCAR, ...