Theoretical Design of Open-Shell Singlet Molecular Systems for Nonlinear Optics

Masayoshi Nakano, Benoît Champagne

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Abstract

Design principles toward open-shell singlet molecular systems exhibiting remarkable nonlinear optical (NLO) responses are derived based on a two-site diradical model within the valence configuration interaction scheme. In this scheme, the concept of diradical character (y), a chemical index for bond weakness in the ground state, enables to classify singlet molecular systems into three categories: (i) closed-shell (y = 0), (ii) intermediate diradical (0 < y < 1), and (iii) pure open-shell (y = 1) systems. It is found that the second hyperpolarizabilities (and also the first hyperpolarizabilities for asymmetric systems) are enhanced in the intermediate diradical character region with respect to the other ones. This leads to a new class of open-shell singlet NLO systems, which are expected to outstrip traditional closed-shell NLO systems. On the basis of this principle, practical molecular design guidelines for tuning the diradical characters and, therefore, for achieving large NLO properties are discussed on the basis of first-principles calculations performed on realistic open-shell singlet molecular systems.

Original languageEnglish
Pages (from-to)3236-3256
Number of pages21
JournalJournal of Physical Chemistry Letters
Volume6
Issue number16
DOIs
Publication statusPublished - 20 Aug 2015

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Nonlinear optics
nonlinear optics
Optical systems
Ground state
Optical properties
Tuning
configuration interaction
tuning
valence
optical properties
ground state

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Theoretical Design of Open-Shell Singlet Molecular Systems for Nonlinear Optics. / Nakano, Masayoshi; Champagne, Benoît.

In: Journal of Physical Chemistry Letters, Vol. 6, No. 16, 20.08.2015, p. 3236-3256.

Research output: Contribution to journalArticle

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