# Tag Info

### How big should a supercell be in phonon calculations?

Quick Summary: There's no way around performing a convergence test. However, it is possible to obtain convergence much faster than the Phonopy approach by using nondiagonal supercells [1]. The basic ...
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Accepted

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### "Input forces are not enough to calculate force constants" Phonopy error?

This error (input forces are not enough to calculate force constants) may arise when you are trying to plot the band structure or the density of state plots for some systems. Sometimes setting a ...

### Lattice Thermal conductivity calculation error

Partial Answers To remove this error Error in routine cdiaghg (211): S matrix not positive definite Use PAW pseudopotential files instead of USPP. Make sure the exchange correlational functional are ...
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### Calculating lattice thermal conductivity using Quantum ESPRESSO and phonopy

Some years ago I found the following steps in ResearchGate: You need: QuantumEspresso (QE) Phono3py ShengBTE & thirdorder.py First, you need to create a QE input file (...
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### Can we translate vibrational frequencies at q-points to vibrational frequencies of atoms?

As known [1], the eigenvalues of the dynamical Hessian matrix represent the phonon frequencies, whereas the eigenvectors represent the particular atomic displacement patterns contributing to the ...