From owner-chemistry@ccl.net Wed Nov  3 20:14:01 2010
From: "Jun Zhang coolrainbow^^yahoo.cn" <owner-chemistry-$-server.ccl.net>
To: CCL
Subject: CCL: question on Born-Oppenheimer approx.
Message-Id: <-43065-101103200951-25716-rqHyMoF11oPF6LdbF5wy0Q-$-server.ccl.net>
X-Original-From: Jun Zhang <coolrainbow . yahoo.cn>
Content-Transfer-Encoding: 8bit
Content-Type: text/plain; charset=utf-8
Date: Thu, 4 Nov 2010 08:09:41 +0800 (CST)
MIME-Version: 1.0


Sent to CCL by: Jun Zhang [coolrainbow-*-yahoo.cn]

Hi everyone:
 
 This question is quite fundermental. I share the somewhat
 similar opinion with Ulf Ekstrom. For an isolate molecule in
 vacuo, by time-independent SE beyond the BO approximation
 with bound state condition, e.g. CH3OCH3 and C2H5OH, they of
 ourse have the same form of SE and have the same solutions.
 
 
 BO approximation, although excellent, does not tell us why
 a particular nuclear configuration can be stable (geometry
 optimization is not the answer since the conception of PES
 is within the framework of BO). In my opinion, the
 introduction of BO approximation can be viewed as a "coarse
 grain" decription of the molecule world, i.e. "unknown" of
 the history of the molecule or the rest of the world. The
 stable existence of a specific configuration, CH3OCH3 or
 C2H5OH, might be traced back to a particular initial
 condition at time t=t0, which has made the solution of SE
 might have some special dynamics properties that the time
 evolution of the configuration is very slow. Another
 possibility is that the condense state of material might
 stabilize the molecule, or we may say that it is those
 molecular configurations which can "survive" or "be robust"
 in the environmant are able to be stationary, or as Ulf
 Ekstrom stated, "pointer state". BO approximation that
 fixes a known nuclear configuration, in my point of view,
 is the reduced description of all other "unknowns"
 
 Jun Zhang
 Nankai University
 coolrainbow---yahoo.cn