Non-adiabatic Calculations Of Spectra Of Open-shell Diatomic Molecules

Yurchenko, Sergei N.

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https://hdl.handle.net/2142/111521 Copy

Description

Title

Non-adiabatic Calculations Of Spectra Of Open-shell Diatomic Molecules

Author(s)

Yurchenko, Sergei N.

Issue Date

2021-06-23

Keyword(s)

Theory and Computation

Abstract

%\begin{wrapfigure}{l}{3cm} %\includegraphics[scale=0.2]{Sergey_03.eps} %\end{wrapfigure} Non-adiabatic couplings (NACs) or derivative couplings (DDRs) between nearly degenerate states can be significant or even divergent. NACs arise from nuclear gradients of electronic wave functions around avoided crossings between adiabatic potential energy curves. Large values of NACs result in strong interaction between corresponding adiabatic states, making the adiabatic approximation invalid. In this work we consider NACs in the case of diatomic open-shell molecules and implement a diabatizaton methodology in the variatonal code \textsc{Duo}.\footnote{S.~N. Yurchenko, L.~Lodi, J.~Tennyson, A.~V. Stolyarov, \emph{Comput. Phys. Commun.}, 2016, \textbf{202}, 262 -- 275; publicly available at \textit{https://github.com/ExoMol}.} The methodology is based on a unitary transformation to the so-called quasi-diabatic states defined to provide smooth (with respect to nuclear coordinates) behaviour of different properties, such as spin-orbit curves, (transition) dipole moment curves etc. As example, rovibronic calculations of the electronic spectra of yttrium oxide, YO,\footnote{A.~N. Smirnov, V.~G. Solomonik, S.~N. Yurchenko, J.~Tennyson, \emph{Phys. Chem. Chem. Phys.}, 2019, \textbf{21}, 22794--22810.} in the quasi-diabatic representation will be presented. \vspace{2cm}

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Permalink

http://hdl.handle.net/2142/111521

DOI

10.15278/isms.2021.WE14

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