[CP2K:9690] What is the use of "CELL_REF"?

[hut... at chem.uzh.ch]

Hi

CP2K uses a 'constant number of plane wave' approach for 
calculations that change the cell volume (cell optimizations and
NPT MD, ...). This means that for expanding cell volumes the 
effective cutoff drops and might be insufficient. 
To avoid this, and to make the calculations independent from
the stating point you can define a reference cell that defines
the total number of plane waves used throughout the calculations.
Common use asks for s reference cell with a volume slightly larger
than the biggest cell expected during the calculation.

regards

Juerg Hutter

PS: when in doubt see the literature about constant pressure
    plane wave calculations from about 2000. 
--------------------------------------------------------------
Juerg Hutter                         Phone : ++41 44 635 4491
Institut für Chemie C                FAX   : ++41 44 635 6838
Universität Zürich                   E-mail: hut... at chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

-----cp... at googlegroups.com wrote: -----
To: cp2k <cp... at googlegroups.com>
From: William Tao 
Sent by: cp... at googlegroups.com
Date: 11/17/2017 04:20PM
Subject: [CP2K:9690] What is the use of "CELL_REF"?

Hello,

I am working on the tutorial of Cell optimization for NaCl crystal, and I do not know what is the use of "CELL_REF" keyword/subsection.

Could anyone tell me about this?

Thank you.

William   
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