Sent to CCL
by: "Georg Lefkidis" [lefkidis^^physik.uni-kl.de]
Dear Jürgen, dear
all
the problem of defining static vs. dynamical correlations is not an
easy
one. I have discussed it many times with my physicists colleagues and
the
consensus (for whatever this is worth) is that dynamic correlations
are
defined by virtual excitations with well-defined, nonzero
energy
differences. Following this trail of thoughts the
“measure” of the character
of the correlations is the energy
difference of the Slater determinants in
the CI expansion. This is also
consistent with the fact that for static
correlations one needs
multi-reference expansions. This is also connected to
the self-energy, in
that the static correlations stem from its imaginary
part while dynamic
mainly originate from its real part. I am not sure I
completely
understand this, however. My interpretation is that since the
static
correlations have no energy difference in the denominator of
the
Green’s function, they can only be imaginary thus leading to
broadening,
while the energy shifting comes from the real part. In view of
this I
probably agree with the statement that static correlations mean
basically
splitting while dynamic basically shifting.
What do you
think?
Best regards
Georg
On
15/03/2012, at 9:23 AM, Jürgen Gräfenstein jurgen-$-chem.gu.se
wrote:
Your point about
quasi-deneracy merits some more thought. So,
you're
suggesting that when the broadening of the energies by
the correlation is
smaller than their splitting, the >correlation is
"dynamic"? Maybe a
self-energy concept can be leveraged
here.
-= This is automatically added to each message by the
mailing script =-
To recover the email address of the author of the message,
please change
the strange characters on the top line to the ~~ sign. You can
also
look up the X-Original-From: line in the mail header.
E-mail to
subscribers:
CHEMISTRY~~ccl.net or use:
http://www.ccl.net/cgi-bin/ccl/send_ccl_messageE-mail to
administrators:
CHEMISTRY-REQUEST~~ccl.net or use
http://www.ccl.net/cgi-bin/ccl/send_ccl_message
http://www.ccl.net/chemistry/sub_unsub.shtml
Before posting, check
wait time at: http://www.ccl.net
Job: http://www.ccl.net/jobs
Conferences: http://server.ccl.net/chemistry/announcements/conferences/
Search
Messages: http://www.ccl.net/chemistry/searchccl/index.shtml
If your mail
bounces > from CCL with 5.7.1 error, check:
http://www.ccl.net/spammers.txt
RTFI: http://www.ccl.net/chemistry/aboutccl/instructions/