[CPMD-list] path integral: normal & staging modes; electron thermostat

[Axel Kohlmeyer]

On Thu, 21 Jul 2005, Lan-Feng Yuan (lyuan at Princeton.EDU) wrote:

LY>   Dear CPMD community,

hi lan-feng,

LY>   First thanks a lot for your information helping me in path integral
LY> calculations. Here I have 2 more questions.

LY>    There are 2 keywords "NORMAL MODES" and "STAGING", corresponding to
LY> using normal modes and staging transforms instead of primitive
LY> coordinates. But when I try to use either of them (with a "1.0" in the
LY> line below to determine masses), the calculation always crashes after
LY> the 1st step:
LY> 
LY>  MODE TRANSFORMED MASSES
LY>   TYPE       REAL MASS        FICTITIOUS MASS FOR IP
LY>    O         15.9949          15.9949              1
LY>    O         31.9898          31.9898              2
LY>    O         23.9924          23.9924              3
LY>    O         21.3266          21.3266              4
LY>    O         19.9936          19.9936              5
LY>    O         19.1939          19.1939              6
LY> ...
LY> 
LY>     NFI  EKINC/P  TEMP   EKINP(PRI)  EKINP(VIR)      EKS/P      EQUANT    ECLASSIC        EHAM     TCPU
LY>       1 0.00000    1.2    -0.00441     0.04152   -17.11631   -17.12072   -16.79543   -16.79543    28.32
LY> p0_20423:  p4_error: interrupt SIGSEGV: 11
LY> 
LY>   What's the problem?

i cannot tell. i am no expert on path-integrals (there is one
a few offices down the hall, but he is not available currently).
would you mind posting your input, so we can check whether there
is a technical problem, i.e. it runs fine on a different machine.

LY>   The other question is whether I should use electronic thermostat for
LY> insulators. For a normal Car-Parrinello MD, there is no need. Is there
LY> some reason that it is needed for PIMD?

yes, there is. the movement of your replica is in the same frequency
region than that of your fictitious electron dynamics, so you need
careful thermostatting to maintain adiabacity. the only alternative
would be a path integral BO-MD...


best regards,
	axel.

LY> 
LY>   Thank you very much! Best regards,
LY> 
LY>   Lan-Feng
LY> 
LY> ----------------------------
LY> Dr. Lan-Feng Yuan,
LY> Postdoctoral Associate,
LY> Department of Chemistry,
LY> Princeton University,
LY> Princeton, NJ 08544, USA
LY> Office Phone: 1-609-258-1834
LY> Fax: 1-609-258-6746
LY> ----------------------------
LY> 
LY> _______________________________________________
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LY> CPMD-list at cpmd.org
LY> http://cpmd.org/mailman/listinfo/cpmd-list
LY> 
LY> 

-- 

=======================================================================
Dr. 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/
=======================================================================
If you make something idiot-proof, the universe creates a better idiot.