[CPMD-list] LMAX

[Axel Kohlmeyer]

On Mon, 11 Jul 2005, Isaac Tamblyn wrote:

IT> Hello,

isaac,

please have a look at the Q&A section of the manual. this already
answeres a large part of your question. see.

http://www.cpmd.org/manual/node106.html#faqwhichLMAX

btw: one tip for everybody. if you want to search the manual
_and_ the mailing list archives at the same time, you can 
(ab-)use google for that. in this case you could use the query

LMAX site:cpmd.org

to find some useful hints.

IT> I have a question about the parameter LMAX. What exactly does this
IT> mean. Should it be set to the highest channel calculated in your psp
IT> file, or is it

LMAX is the highest angular momentum that is considered for 
the given pseudopotential. unless explicitely specified with
LOCAL, it also selects the potential chosen as the local potential 
for the kleinman-bylander separation.

IT> something different. The reason that I ask is that I have a psp for
IT> which I have calculated both s and p channels, yet the results I get
IT> for LMAX=S "make more sense" (they are consistent with other codes
IT> where this parameter does not need to be specified).

you may want to check how much sense your results make, if you 
add LOCAL=S to use the s-channel as the local potential.

also, you should check whether the potential for the p-channel
makes physical sense, or if you have ghost states if you use 
the p-potential as local potential. finally, you should check
if the p-state is bound in the all electron calculation (i assume it 
is empty), if not it sometimes improves the potential a lot,
by using the p-channel from an all-electron run with a different
occupation scheme, or simply use a slightly ionized configuration
and/or use a fractional occupation in the p-channel.
it may help, if you would tell us which element this concerns.

best regards,
	axel.
IT> 
IT> Thanks in advance,
IT> 
IT> Isaac
IT> _______________________________________________
IT> CPMD-list mailing list
IT> CPMD-list at cpmd.org
IT> http://cpmd.org/mailman/listinfo/cpmd-list
IT> 
IT> 

-- 

=======================================================================
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.