what is the physical meaning of cutoff and rel_cutoff

[Penghchao Zhang]

Dear CP2K group,

The way I see it, cutoff is for charge and rel_cutoff is for orbitals. Do you think this is correct? Or could you please explain more about the physical meaning of cutoff and rel_cutoff, do they just have a numerical meaning? (as shown in https://www.cp2k.org/howto:converging_cutoff#converging_rel_cutoff)

Thanks in advance!

[Jürg Hutter]

Hi

CUTOFF is the plane wave cutoff used to expand the total density.
REL_CUTOFF is the cutoff used to expand a Gaussian with exponent 1.
This is needed for the multi-grid algorithm where each Gaussian is
integrated on a grid according to its exponent.

regards
JH

________________________________________
From: cp...@googlegroups.com <cp...@googlegroups.com> on behalf of Penghchao Zhang <pczha...@gmail.com>
Sent: Saturday, October 14, 2023 5:33 AM
To: cp2k
Subject: [CP2K:19364] what is the physical meaning of cutoff and rel_cutoff

Dear CP2K group,

The way I see it, cutoff is for charge and rel_cutoff is for orbitals. Do you think this is correct? Or could you please explain more about the physical meaning of cutoff and rel_cutoff, do they just have a numerical meaning? (as shown in https://www.cp2k.org/howto:converging_cutoff#converging_rel_cutoff)

Thanks in advance!

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[Vahiya Mitanshu]

What will be the difference for low cutoff value and high or default cutoff value. Means I'm performing one system at cutoff value 10 and another at 280 or higher. How it will going to affect the result? 

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