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**General Questions and Answers / Setting max_interaction_range for phonon dispersion**

« **on:**March 18, 2023, 15:17 »

Hi,

What general guidelines should be followed when setting "max_interaction_range" for phonon dispersion calculations to achieve reliable results, taking into account its effects on supercell size and the occurrence of imaginary frequencies? Specifically, when using the default interaction range, larger supercells are suggested while specifying a smaller max_interaction_range leads to smaller supercells Furthermore, the choice of interaction range can influence the presence or absence of imaginary frequencies in different cases.

For some systems, the lower interaction range manages to eliminate imaginary frequencies, while the default value of the interaction range shows imaginary frequencies, and there are some cases in which situations got reversed i.e default interaction range eliminates imaginary frequency and the lower interaction range does not.

So, is there any general rule which needs to be followed while calculating reliable phonon dispersion?

Best regard,

krabidix

What general guidelines should be followed when setting "max_interaction_range" for phonon dispersion calculations to achieve reliable results, taking into account its effects on supercell size and the occurrence of imaginary frequencies? Specifically, when using the default interaction range, larger supercells are suggested

Code

`repetitions = checkNumberOfRepetitions(bulk_configuration),`

Code

`repetitions = checkNumberOfRepetitions(bulk_configuration, max_interaction_range=5.0*Angstrom).`

For some systems, the lower interaction range manages to eliminate imaginary frequencies, while the default value of the interaction range shows imaginary frequencies, and there are some cases in which situations got reversed i.e default interaction range eliminates imaginary frequency and the lower interaction range does not.

So, is there any general rule which needs to be followed while calculating reliable phonon dispersion?

Best regard,

krabidix