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Title:Fit point-wise ab initio calculation potential energies to a multi-dimension morse/long-range model
Author(s):Zhai, Yu
Contributor(s):Le Roy, Robert J.; Li, Hui
Subject(s):Spectroscopy of Large Amplitude Motions
Abstract:\begin{wrapfigure}{r}{0pt} \includegraphics[scale=0.35]{mdmlr.eps} \end{wrapfigure} A potential energy surface (PES) is a fundamental tool and source of understanding for theoretical spectroscopy and for dynamical simulations. Making correct assignments for high-resolution rovibrational spectra of floppy polyatomic and van der Waals molecules often relies heavily on predictions generated from a high quality {\it ab initio} potential energy surface. Moreover, having an effective analytic model to represent such surfaces can be as important as the {\it ab initio} results themselves. For the one-dimensional potentials of diatomic molecules, the most successful such model to date is arguably the ``Morse/Long-Range'' (MLR) function developed by R.~J. Le~Roy and coworkers.\footnote{{\it Mol. Phys.} {\bf 105}, 663 (2007)
{\it J. Chem. Phys.} {\bf 131}, 204309 (2009)
{\it Mol.\ Phys.}\ {\bf 109}, 435 (2011).} It is very flexible, is everywhere differentiable to all orders. It incorporates correct predicted long-range behaviour, extrapolates sensibly at both large and small distances, and two of its defining parameters are always the physically meaningful well depth ${D}_e$ and equilibrium distance $r_e$. Extensions of this model, called the Multi-Dimension Morse/Long-Range (MD-MLR) function, %have been applied successfully to atom-plus-linear molecule systems\footnote{{\it Phys.\ Chem.\ Chem.\ Phys.}\ {\bf 10}, 4128 (2008)
{\it J.\ Chem.\ Phys.}\ {\bf 130}, 144305 (2009)}, linear molecule--linear molecule systems\footnote{{\it J. Chem. Phys.} {\bf 132}, 214309 (2010).} and atom--non-linear molecule\footnote{{\it J. Chem. Phys.} {\bf 140}, 214309 (2010).} system. have been applied successfully to atom-plus-linear molecule, linear molecule--linear molecule and atom--non-linear molecule systems.\footnote{{\it Phys.\ Chem.\ Chem.\ Phys.}\ {\bf 10}, 4128 (2008)
{\it J.\ Chem.\ Phys.}\ {\bf 130}, 144305 (2009)
{\it J. Chem. Phys.} {\bf 132}, 214309 (2010)
{\it J. Chem. Phys.} {\bf 140}, 214309 (2014)
{\it J. Chem. Phys.} {\bf 144}, 014301 (2016).} However, there are several technical challenges faced in modelling the interactions of general molecule-molecule systems, such as the absence of radial minima for some relative alignments, difficulties in fitting short-range potential energies, and challenges in determining relative-orientation dependent long-range coefficients. This talk will illustrate some of these challenges and describe our ongoing work in addressing them.
Issue Date:2016-06-20
Publisher:International Symposium on Molecular Spectroscopy
Genre:Conference Paper/Presentation
Rights Information:Copyright 2016 by the authors
Date Available in IDEALS:2017-01-26

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