[Faculty] Fwd: [CSRC-SDSU COLLOQUIUM]: A Good Method to Avoid for Treating Internal Rotation in the Partition Function

[Jose Castillo]

DATE: Friday, September 27th, 2013

TITLE: A Good Method to Avoid for Treating Internal Rotation in the
Partition Function

TIME: 3:30 PM
LOCATION: GMCS 214

SPEAKER: Dr. Andrew Cooksy. San Diego State University

Our software package FEMvib solves the vibrational Schrodinger equation in
up to three dimensions on an arbitrary potential energy surface. This
analysis allows us to predict vibrational excitation energies in molecules,
starting from now-routine electronic structure calculations, in cases where
the potential energy is poorly modeled by common approximations (in
particular, where the potential is highly anharmonic and where coupling
between degrees of freedom varies strongly with excitation). We recently
applied FEMvib to a system with coupled internal rotations (two groups
spinning about neighboring single bonds) in a small oxyhydrocarbon. The
intention is to test several methods for approximating the contribution to
the molecular partition function from these motions. Accurate partition
functions are needed to estimate the thermodynamic parameters of molecules
in combustion chemistry, and these easily excited internal rotations now
account for the dominant error in our ability to predict many of those
partition functions. Our results, based on explicit calculations of the
partition function from the manifold of quantum states, fall between those
from typical approximation methods, but also demonstrate why a fully
quantum solution is not feasible in most cases, especially at the
temperatures relevant to combustion.

HOST: Dr. Jose Castillo

For future events, please visit our website at:

http://www.csrc.sdsu.edu/colloquium.html



-- 

Jose E. Castillo  Ph.D.

Director / Professor

Computational Science Research Center

5500 Campanile Dr

San Diego State University

San Diego CA 92182-1245

619 5947205/3430, Fax 619-594-2459

 http://www.csrc.sdsu.edu/mimetic-book/

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