Author Topic: Phonon transmission spectrum  (Read 90 times)

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Offline Wisam1222

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Phonon transmission spectrum
« on: November 14, 2020, 10:16 »
Dear ATK users
I would like to calculate phonon transmission spectrum for Device (In the attached file 1), the parameters below have been used:
Calculator type and parameters:
ATK-DFT: LCAO (Device) calculator
Density mesh cut-off: (75)
Exchange correlation: LDA
K-point sampling: (3x3x100)
Phonon transmission spectrum: q-point sampling 5x5
Unfortunately, this problem appears:  ""Memory Error: Unable to allocate the required storage. This is probably caused by insufficient available memory"".
Note that the specifications of the computer used are:
Processor: Intel(R) Xeon(R) CPU E5-2690 v2 @ 3.00GHz   3.00 GHz  (2 processors), 20 cores, Logical processors 40.
RAM: 48 GB.
Please help me in solving this problem.

Best Regards

Offline Anders Blom

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Re: Phonon transmission spectrum
« Reply #1 on: November 19, 2020, 09:10 »
You are using an old version which is no longer supported, but the main problem (although we cannot see you input script) is probably that with your settings a lot of DFT calculations are started at the same time, on that single machine. Each supercell for the dynamical matrix will be 5x5x1 times the original one, which is a very large calculation. Unless you tell the program to only run 1 displacement per node, it will almost certainly run out of memory. In newer versions the default has been updated, but in older version, set the keyword processes_per_displacement in HamiltonianDerivatives/DynamicaMatrix to the number of MPI processes (or number of cores per node, if you run over many nodes) to avoid this.