scholarly journals Ultrafast and radiationless electronic excited state decay of uracil and thymine cations: computing the effects of dynamic electron correlation

2019 ◽  
Vol 21 (26) ◽  
pp. 14322-14330 ◽  
Author(s):  
Javier Segarra-Martí ◽  
Thierry Tran ◽  
Michael J. Bearpark

In this article we characterise the radiationless decay of the first few electronic excited states of the cations of DNA/RNA nucleobases uracil and thymine, including the effects of dynamic electron correlation on energies and geometries (optimised with XMS-CASPT2).

2018 ◽  
Author(s):  
Juan Sanz García ◽  
Martial Boggio-Pasqua ◽  
Ilaria Ciofini ◽  
Marco Campetella

<div>The ability to locate minima on electronic excited states (ESs) potential energy surfaces (PESs) both in the case of bright and dark states is crucial for a full understanding of photochemical reactions. This task has become a standard practice for small- to medium-sized organic chromophores thanks to the constant developments in the field of computational photochemistry. However, this remains a very challenging effort when it comes to the optimization of ESs of transition metal complexes (TMCs), not only due to the presence of several electronic excited states close in energy, but also due to the complex nature of the excited states involved. In this article, we present a simple yet powerful method to follow an excited state of interest during a structural optimization in the case of TMC, based on the use of a compact hole-particle representation of the electronic transition, namely the natural transition orbitals (NTOs). State tracking using NTOs is unambiguously accomplished by computing the mono-electronic wavefunction overlap between consecutive steps of the optimization. Here, we demonstrate that this simple but robust procedure works not only in the case of the cytosine but also in the case of the ES optimization of a ruthenium-nitrosyl complex which is very problematic with standard approaches.</div>


2019 ◽  
Author(s):  
Artur Nowak ◽  
Paweł Tecmer ◽  
Katharina Boguslawski

<p>We present a benchmark study of the performance of various recently presented EOM-pCCD-based methods to model ground and excited state properties of a set of f0 actinide species that feature different types of electronic excitations, like local excitations or charge transfer. Our data suggests that the recently developed EOM-pCCD-LCCSD method outperforms conventional approaches like EOM-CCSD reducing the standard error by a factor of 2 (to 0.25 eV). Thus, EOM-pCCD-LCCSD can be considered as an alternative to model excited states in challenging systems, especially those who feature a double electron transfer for which EOM-CCSD typically fails.</p>


1992 ◽  
Vol 247 ◽  
Author(s):  
J. R. Heflem ◽  
Q. L. Zhou ◽  
D. C. Rodenberger ◽  
Y. M. Cai ◽  
A. F. Garito

ABSTRACTA general enhancement mechanism is discussed for nonlinear optical processes originating from real population of electronic excited states. Enhancement of greater than two orders of magnitude of nonresonant third harmonic generation from an optically pumped s1 electronic excited state is experimentally observed in a conjugated disc-like metallophthalocyanine.


2016 ◽  
Vol 18 (16) ◽  
pp. 11443-11453 ◽  
Author(s):  
Takeshi Miki ◽  
Tiago Buckup ◽  
Marie S. Krause ◽  
June Southall ◽  
Richard J. Cogdell ◽  
...  

The ultrafast femtochemistry of carotenoids is governed by the interaction between electronic excited states, which has been explained by the relaxation dynamics within a few hundred femtoseconds from the lowest optically allowed excited state S2to the optically dark state S1.


2019 ◽  
Author(s):  
Artur Nowak ◽  
Paweł Tecmer ◽  
Katharina Boguslawski

<p>We present a benchmark study of the performance of various recently presented EOM-pCCD-based methods to model ground and excited state properties of a set of f0 actinide species that feature different types of electronic excitations, like local excitations or charge transfer. Our data suggests that the recently developed EOM-pCCD-LCCSD method outperforms conventional approaches like EOM-CCSD reducing the standard error by a factor of 2 (to 0.25 eV). Thus, EOM-pCCD-LCCSD can be considered as an alternative to model excited states in challenging systems, especially those who feature a double electron transfer for which EOM-CCSD typically fails.</p>


2018 ◽  
Vol 20 (22) ◽  
pp. 15074-15085 ◽  
Author(s):  
Peter S. Sherin ◽  
Yuri P. Tsentalovich ◽  
Eric Vauthey ◽  
Enrico Benassi

An unsaturated bond in the side chain leads to the ultrafast decay of the excited statesviaa conical intersection independent of solvent properties.


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