# Tag Info

8

For system with small strain condition, energy of strained system can be written in Taylor series as $$E(\epsilon)=E(0)+\frac{V_0}{2}\sum_{ijk}C_{ijkl}\epsilon_{ij}\epsilon_{kl}+...$$ In Voigt notation, It can be written as $$E(\epsilon)=E(0)+\frac{V_0}{2}C_{ij}\epsilon_{i}\epsilon_{j}+...$$ or E(\epsilon)=E(0)+\boldsymbol{\epsilon}^T\mathbf{C}\boldsymbol{\...

7

I have looked into this a bit, I think in general it is ill-advised to mix codes like this unless it is needed, but VASP does not support self-consistent hubbard U (no perturbations at non-zero U). As long as you can prove the two codes produce the same results, it is probably okay. Specifically, if you can prove the property of interest is the same at U=0 ...

6

I am by no means a DFT expert, so another may be able to provide a better/more complete answer. Nevertheless... short answer: The local density approximation (or its leading gradient extension) do not hold in the limit of a Mott insulator. This being because the Mott insulator is constructed from occupying maximally-localized electron orbitals, and therefore ...

4

I don't have a chance to give a complete answer and this may not be as fitting since you are intending to use a planewave based code, but this paper [1] gives a good description of computing the forces on a solid for an AO basis calculation. In general, relaxing lattice parameters isn't all that different from a general geometry optimization. Assuming (for ...

4

It looks like Quantum Espresso is available through conda-forge which will be helpful. Conda Forge has worked to migrate many packages to osx-arm64 and will rebuild packages for you. The easy way is to update the list of packages to migrate as a pull-request. Assuming that goes through, various scripts will update the qe package on conda-forge and you'll get ...

4

To play with parameters or vectors of unit cell, you can use following tag inside &CELL cell_dofree CHARACTER Default: 'all' Select which of the cell parameters should be moved: 'all' : all axis and angles are moved 'ibrav' : all axis and angles are moved, but the lattice remains consistent with the initial ibrav choice. ...

3

I notice you are using Hubbard U in your input file and you are not using the same Hubbard U in both, which is probably good. However, you might consider if using a larger U value does give you the same result in VASP. These results could be sensitive to this parameter. You may also want to actually show the spin resolved PDOS for both codes, that might ...

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