[CP2K:8961] calculation of a x-ray structure

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

Hi

I would just do a periodic calculation (using the cif file).
You get all the packing effects and the computational costs
are not higher (or even lower) than for a cluster calculation.

regards

Juerg
--------------------------------------------------------------
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
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-----cp... at googlegroups.com wrote: -----To: cp2k <cp... at googlegroups.com>
From: Jörg Saßmannshausen 
Sent by: cp... at googlegroups.com
Date: 04/21/2017 01:17PM
Subject: [CP2K:8961] calculation of a x-ray structure

Dear all,

when I am usually calculate structures from the data I am obtaining via a x-
ray analysis, i.e. from the CIF file, I simply take the single molecule and run 
that via some DFT functional. No periodic boundries, if there are two 
molecules in the unit cell I simply pick one. 

However, to find out whether a specific effect I am seeing is due to crystal 
packing or not, I actually want to calculate the complete unit cell, which 
contains two molecules, and I want to calculated it as a lattice, i.e. one 
more cell in each direction. This way, I hope, I would see whether it is due 
to crystal packing effects what I am observing, or not. 

>From the CIF file I know it is a triclinic cell and I also know the geometric 
parameters, i.e. a,b,c and the angles.

If I plug that into the subsys section of the input file and I am using the MT 
POISSON_SOLVER, what else do I need to bear in mind? 
Does that actually make sense what I am trying to do or is that a waste of my 
time? I never done solid state calculations as I am more a single molecule 
person so your advice here would be much appreciated. 

Please let me know if you got any further questions.

All the best from a dull London

Jörg

-- 
*************************************************************
Dr. Jörg Saßmannshausen, MRSC
University College London
Department of Chemistry
20 Gordon Street
London
WC1H 0AJ 

email: j.sassma... at ucl.ac.uk
web: http://sassy.formativ.net

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