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Photochemistry in Real Space: Batho‐ and Hypsochromism in the Water Dimer
Author(s) -
FernándezAlarcón Alberto,
GuevaraVela José Manuel,
CasalsSainz José Luis,
Costales Aurora,
Francisco Evelio,
Martín Pendás Ángel,
Rocha Rinza Tomás
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202002854
Subject(s) - excited state , water dimer , dimer , intuition , intermolecular force , bathochromic shift , coupled cluster , molecule , chemical physics , dipole , chemistry , theoretical physics , physics , quantum mechanics , atomic physics , computational chemistry , hydrogen bond , philosophy , organic chemistry , epistemology , fluorescence
The development of chemical intuition in photochemistry faces several difficulties that result from the inadequacy of the one‐particle picture, the Born–Oppenheimer approximation, and other basic ideas used to build models. It is shown herein how real‐space approaches can be efficiently used to gain valuable insights in photochemistry through a simple example of red and blue shift effects: the double hypso‐ and bathochromic shifts in the low‐lying valence excited states of (H 2 O) 2 . It is demonstrated that 1) the use of these techniques allows the perturbative language used in the theory of intermolecular interactions, even in the strongly interacting short‐range regime, to be maintained; 2) one and only one molecule is photoexcited in each of the addressed excited states and 3) the electrostatic interaction between the in‐the‐cluster molecular dipoles provides a fairly intuitive rationalisation of the observed batho‐ and hypsochromism. The methods exploited and illustrated herein are able to maintain the individuality and properties of the interacting entities in a molecular aggregate, and thereby they allow chemical intuition in general states, at any geometry and using a broad variety of electronic structure methods to be kept and built.