[CPMD-list] path integral

[Ivan Ivanov]

Dear Dr.Kohlmeyer,
 
First of all - congratulations for the great resource you made available for cpmd users.
 
now to the point:
 
I am not trying to save computational load.
 
The problem is that we want to study the effect of treating some nuclei classically while others as quantum particles;  dissection of quantum and thermal fluctuations etc.   This is part of the research.
 
So, please, if someone has practical hints how to do this with CPMD - help us.
 
Sincerely,
Iv

Axel Kohlmeyer <axel.kohlmeyer at theochem.ruhr-uni-bochum.de> wrote:

>>> "II" == Ivan Ivanov writes:

II> Dear CPMD users,

II> 1.How do I select nuclei for PATH INTEGRAL
II> simulations?

II> e.g I want to treat only 1 nucleus as "quantum",
II> others behaving classically.

hello ivan,

may i ask, what would you want to achieve by that?

i don't think that you would save any significant 
computational effort by that. the way path integral
is implemented in cpmd, you basically run a 'regular' 
BO- or CP-MD simulation of the whole system for each 
replica. so it should not make a difference if only 
one or many of the nuclei are treated as 'quantum'.

II> The manual describes the situation where all nuclei
II> are
II> treated as "quantum".

II> 2. Does anyone have experience with using PATH
II> INTEGRAL 
II> SIMULATION coupled with using EXTERNAL POTENTIAL
II> option?

i don't know whether someone has tried this yet, but 
due to the way path integral is implemented (see above).
there is a good chance that i will work, or may only 
need rather small changes to the source code to make 
it work.

II> More generally - Is CPMD suitable for studying quantum
II> behaviour of nuclei under external electrostatic
II> field?

yes. you may want to contact Rodolphe Vuilleumier
, since
he has recently contributed some code for that kind 
of computation to the current cpmd development version.

hope this helps,
axel kohlmeyer.

II> Thanks for your answers!
II> Iv








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=======================================================================
Axel Kohlmeyer e-mail: axel.kohlmeyer at theochem.ruhr-uni-bochum.de
Lehrstuhl fuer Theoretische Chemie Phone: ++49 (0)234/32-26673
Ruhr-Universitaet Bochum - NC 03/53 Fax: ++49 (0)234/32-14045
D-44780 Bochum http://www.theochem.ruhr-uni-bochum.de/~axel.kohlmeyer/
=======================================================================
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