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Roca-Sanjuán, D., Francés-Monerris, A., Fernández Galván, I., Farahani, P., Lindh, R. & Liu, Y.-J. (2017). Advances in computational photochemistry and chemiluminescence of biological and nanotechnological molecules. In: Angelo Albini, Elisa Fasani (Ed.), Photochemistry: Volume 44: (pp. 16-60). Cambridge, UK: Royal Society of Chemistry.
Open this publication in new window or tab >>Advances in computational photochemistry and chemiluminescence of biological and nanotechnological molecules
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2017 (English)In: Photochemistry: Volume 44 / [ed] Angelo Albini, Elisa Fasani, Cambridge, UK: Royal Society of Chemistry, 2017, 16-60 p.Chapter in book (Other academic)
Abstract [en]

Recent advances (2014–2015) in computational photochemistry and chemiluminescence derive from the development of theory and from the application of state-of-the-art and new methodology to challenging electronic-structure problems. Method developments have mainly focused, first, on the improvement of approximate and cheap methods to provide a better description of non-adiabatic processes, second, on the modification of accurate methods in order to decrease the computation time and, finally, on dynamics approaches able to provide information that can be directly compared with experimental data, such as yields and lifetimes. Applications of the ab initio quantum-chemistry methods have given rise to relevant findings in distinct fields of the excited-state chemistry. We briefly summarise, in this chapter, the achievements on photochemical mechanisms and chemically-induced excited-state phenomena of interest in biology and nanotechnology.

Place, publisher, year, edition, pages
Cambridge, UK: Royal Society of Chemistry, 2017
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-336863 (URN)10.1039/9781782626954-00016 (DOI)978-1-78262-543-8 (ISBN)
Available from: 2017-12-18 Created: 2017-12-18 Last updated: 2017-12-28
Sørensen, L. K., Guo, M., Lindh, R. & Lundberg, M. (2017). Applications to metal K pre-edges of transitionmetal dimers illustrate the approximate origin independence for the intensities in the length representation. Molecular Physics, 115(1-2), 174-189.
Open this publication in new window or tab >>Applications to metal K pre-edges of transitionmetal dimers illustrate the approximate origin independence for the intensities in the length representation
2017 (English)In: Molecular Physics, ISSN 0026-8976, E-ISSN 1362-3028, Vol. 115, no 1-2, 174-189 p.Article in journal (Refereed) Published
Abstract [en]

X-ray absorption spectroscopy (XAS) in the metal K pre-edge is a standard probe of electronic and geometric structure of transition metal complexes. Simulating the K pre-edge spectra requires contributions beyond the electric dipole, but if that term is non-zero, the second-order terms, e. g. electric quadrupoles, are no longer origin-independent. In the velocity representation, complete origin independence can be achieved by including all terms to the same order in the oscillator strength. Here, we implement that approach in the length representation and use it for restricted active space (RAS) simulations of metal K pre-edges of iron monomers and dimers. Complete origin independence is not achieved and the size of the remaining errors depends on the electric dipole oscillator strength and its ratio in length and velocity representations. The error in the origin independence is in the ANO basis sets two orders of magnitude smaller than the value of the individual contributions. For systemswith strong electric dipole contributions, the errors are not significant within 3 angstrom from a metal centre, far enough to handlemany multi-metal systems. Furthermore, we discuss the convergence of the multipole expansion, the possibility to assign spectral contributions, and the origin of negative absorption intensities. [GRAPHICS]

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2017
Keyword
Multiconfigurational wavefunction, oscillator strengths, quadrupole intensities, properties, X-ray spectroscopy
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-319774 (URN)10.1080/00268976.2016.1225993 (DOI)000396794700015 ()
Funder
Knut and Alice Wallenberg Foundation, KAW-2013.0020Swedish Research Council, 2012-3910 2012-3924
Available from: 2017-04-12 Created: 2017-04-12 Last updated: 2017-11-29Bibliographically approved
Vacher, M., Brakestad, A., Karlsson, H. O., Fernández Galván, I. & Lindh, R. (2017). Dynamical Insights into the Decomposition of 1,2-Dioxetane. Journal of Chemical Theory and Computation, 13(6), 2448-2457.
Open this publication in new window or tab >>Dynamical Insights into the Decomposition of 1,2-Dioxetane
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2017 (English)In: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 13, no 6, 2448-2457 p.Article in journal (Refereed) Published
Abstract [en]

Chemiluminescence in 1,2-dioxetane occurs through a thermally activated decomposition reaction into two formaldehyde molecules. Both ground-state and nonadiabatic dynamics (including singlet excited states) of the decomposition reaction have been simulated, starting from the first O–O bond-breaking transition structure. The ground-state dissociation occurs between t = 30 fs and t = 140 fs. The so-called entropic trap leads to frustrated dissociations, postponing the decomposition reaction. Specific geometrical conditions are necessary for the trajectories to escape from the entropic trap and for dissociation to be possible. The singlet excited states participate as well in the trapping of the molecule: dissociation including the nonadiabatic transitions to singlet excited states now occurs from t = 30 fs to t = 250 fs and later. Specific regions of the seam of the So/S1 conical intersections that would "retain" the molecule for longer on the excited state have been identified.

National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-329717 (URN)10.1021/acs.jctc.7b00198 (DOI)000403530100009 ()28437611 (PubMedID)
Funder
Swedish Research Council, 2012-3910
Available from: 2017-10-02 Created: 2017-10-02 Last updated: 2017-10-02Bibliographically approved
Sörensen, L. K., Lindh, R. & Lundberg, M. (2017). Gauge origin independence in finite basis sets and perturbation theory. Chemical Physics Letters, 683, 536-542.
Open this publication in new window or tab >>Gauge origin independence in finite basis sets and perturbation theory
2017 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 683, 536-542 p.Article in journal (Refereed) Published
Abstract [en]

We show that origin independence in finite basis sets for the oscillator strengths is possibly in any gauge contrary to what is stated in literature. This is proved from a discussion of the consequences in perturbation theory when the exact eigenfunctions and eigenvalues to the zeroth order Hamiltonian H-0 cannot be found. We demonstrate that the erroneous conclusion for the lack of gauge origin independence in the length gauge stems from not transforming the magnetic terms in the multipole expansion leading to the use of a mixed gauge. Numerical examples of exact origin dependence are shown.

Keyword
Gauge origin independence, Finite basis sets, Perturbation theory, Oscillator strengths, X-ray spectroscopy
National Category
Physical Sciences Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-333065 (URN)10.1016/j.cplett.2017.05.003 (DOI)000405802200086 ()
Funder
Knut and Alice Wallenberg Foundation, KAW-2013.0020Swedish Research Council, 2012-3910, 2012-3924Swedish National Infrastructure for Computing (SNIC), snic2014-5-36, snic2015-4-71, snic2015-1-465, snic2015-1427
Available from: 2017-11-09 Created: 2017-11-09 Last updated: 2017-11-09Bibliographically approved
Vacher, M., Farahani, P., Valentini, A., Frutos, L. M., Karlsson, H. O., Fernández Galván, I. & Lindh, R. (2017). How Do Methyl Groups Enhance the Triplet Chemiexcitation Yield of Dioxetane?. Journal of Physical Chemistry Letters, 8(16), 3790-3794.
Open this publication in new window or tab >>How Do Methyl Groups Enhance the Triplet Chemiexcitation Yield of Dioxetane?
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2017 (English)In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 8, no 16, 3790-3794 p.Article in journal (Refereed) Published
Abstract [en]

Chemiluminescence is the emission of light as a result of a nonadiabatic chemical reaction. The present work is concerned with understanding the yield of chemiluminescence, in particular how it dramatically increases upon methylation of 1,2-dioxetane. Both ground-state and nonadiabatic dynamics (including singlet excited states) of the decomposition reaction of various methyl-substituted dioxetanes have been simulated. Methyl-substitution leads to a significant increase in the dissociation time scale. The rotation around the O-C-C-O dihedral angle is slowed; thus, the molecular system stays longer in the "entropic trap" region. A simple kinetic model is proposed to explain how this leads to a higher chemiluminescence yield. These results have important implications for the design of efficient chemiluminescent systems in medical, environmental, and industrial applications.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2017
National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-334304 (URN)10.1021/acs.jpclett.7b01668 (DOI)000408187400012 ()28749694 (PubMedID)
Funder
Swedish Research Council, 2016-03398
Available from: 2017-11-23 Created: 2017-11-23 Last updated: 2017-11-23Bibliographically approved
Yanai, T., Kurashige, Y., Saitow, M., Chalupsky, J., Lindh, R. & Malmqvist, P.-Å. (2017). Influence of the choice of projection manifolds in the CASPT2 implementation. Molecular Physics, 115(17-18), 2077-2085.
Open this publication in new window or tab >>Influence of the choice of projection manifolds in the CASPT2 implementation
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2017 (English)In: Molecular Physics, ISSN 0026-8976, E-ISSN 1362-3028, Vol. 115, no 17-18, 2077-2085 p.Article in journal (Refereed) Published
Abstract [en]

The Complete Active Space Second-Order Perturbation Theory (CASPT2) is well-established as a high-accuracy electronic structure method. It was originally implemented in the early 1990s to an efficient computer code in the molcas program suite, and this implementation has been extensively used as a standard tool. Here, we report a comparison of it against two independent computer-aided implementations of the CASPT2 method, revealing that the CASPT2 energies provided by the original code of molcas (version 8 or earlier) are inconsistent with the predictions of the lately developed computer-aided implementations. It is shown that this error is associated with the projections of the first-order equation onto the fully internally contracted multireference bases which are partially inconsistent between the left- and right-hand sides. The degree of the errors is assessed by performing illustrative CASPT2 calculations. The errors in total CASPT2 energies are demonstrated to be negligible relative to chemical accuracy in many cases, while there is a difficult case where they may substantially alter chemical description. The incorporation of the consistent projections into molcas has been carried out, which is available in the version 8 sp1.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2017
Keyword
Multireference theory, CASPT2, MOLCAS, computer-aided programming
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-334508 (URN)10.1080/00268976.2016.1271152 (DOI)000408727700010 ()
Available from: 2017-12-14 Created: 2017-12-14 Last updated: 2017-12-14Bibliographically approved
Aquilante, F., Delcey, M. G., Pedersen, T. B., Fernández Galván, I. & Lindh, R. (2017). Inner projection techniques for the low-cost handling of two-electron integrals in quantum chemistry. Molecular Physics, 115(17-18), 2052-2064.
Open this publication in new window or tab >>Inner projection techniques for the low-cost handling of two-electron integrals in quantum chemistry
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2017 (English)In: Molecular Physics, ISSN 0026-8976, E-ISSN 1362-3028, Vol. 115, no 17-18, 2052-2064 p.Article in journal (Refereed) Published
Abstract [en]

The density-fitting technique for approximating electron-repulsion integrals relies on the quality of auxiliary basis sets. These are commonly obtained through data fitting, an approach that presents some shortcomings. On the other hand, it is possible to derive auxiliary basis sets by removing elements from the product space of both contracted and primitive orbitals by means of a particular form of inner projection technique that has come to be known as Cholesky decomposition (CD). This procedure allows for on-the-fly construction of auxiliary basis sets that may be used in conjunction with any quantum chemical method, i.e. unbiased auxiliary basis sets. One key feature of these sets is that they represent the electron-repulsion integral matrix in atomic orbital basis with an accuracy that can be systematically improved. Another key feature is represented by the fact that locality of fitting coefficients is obtained even with the long-ranged Coulomb metric, as result of integral accuracy. Here we report on recent advances in the development of the CD-based density fitting technology. In particular, the implementation of analytical gradients algorithms is reviewed and the present status of local formulations - potentially linear scaling - is analysed in detail.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2017
Keyword
Quantum chemistry, Lowdin's inner projections, Cholesky decomposition, density fitting, linear scaling
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-334507 (URN)10.1080/00268976.2017.1284354 (DOI)000408727700008 ()
Available from: 2017-12-14 Created: 2017-12-14 Last updated: 2017-12-14Bibliographically approved
Augusto, F. A., Francés-Monerris, A., Fdez. Galván, I., Roca-Sanjuán, D., Bastos, E. L., Baader, W. J. & Lindh, R. (2017). Mechanism of activated chemiluminescence of cyclic peroxides: 1,2-dioxetanes and 1,2-dioxetanones. Physical Chemistry, Chemical Physics - PCCP, 19(5), 3955-3962.
Open this publication in new window or tab >>Mechanism of activated chemiluminescence of cyclic peroxides: 1,2-dioxetanes and 1,2-dioxetanones
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2017 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 5, 3955-3962 p.Article in journal (Refereed) Published
Abstract [en]

Almost all chemiluminescent and bioluminescent reactions involve cyclic peroxides. The structure of the peroxide and reaction conditions determine the quantum efficiency of light emission. Oxidizable fluorophores, the so-called activators, react with 1,2-dioxetanones promoting the former to their first singlet excited state. This transformation is inefficient and does not occur with 1,2-dioxetanes; however, they have been used as models for the efficient firefly bioluminescence. In this work, we use the SA-CASSCF/CASPT2 method to investigate the activated chemiexcitation of the parent 1,2-dioxetane and 1,2-dioxetanone. Our findings suggest that ground state decomposition of the peroxide competes efficiently with the chemiexcitation pathway, in agreement with the available experimental data. The formation of non-emissive triplet excited species is proposed to explain the low emission efficiency of the activated decomposition of 1,2-dioxetanone. Chemiexcitation is rationalized considering a peroxide/activator supermolecule undergoing an electron-transfer reaction followed by internal conversion.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2017
National Category
Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:uu:diva-320470 (URN)10.1039/c6cp08154a (DOI)000395328100057 ()28106183 (PubMedID)
Available from: 2017-04-20 Created: 2017-04-20 Last updated: 2017-12-18
Francés-Monerris, A., Fernández Galván, I., Lindh, R. & Roca-Sanjuan, D. (2017). Triplet versus singlet chemiexcitation mechanism in dioxetanone: a CASSCF/CASPT2 study. Theoretical Chemistry accounts, 136(6), Article ID 70.
Open this publication in new window or tab >>Triplet versus singlet chemiexcitation mechanism in dioxetanone: a CASSCF/CASPT2 study
2017 (English)In: Theoretical Chemistry accounts, ISSN 1432-881X, E-ISSN 1432-2234, Vol. 136, no 6, 70Article in journal (Refereed) Published
Abstract [en]

Chemiluminescence is a fundamental process of chemistry consisting in the conversion of chemical energy stored in chemical bonds into light. It is used by nature and by man-made technology, being especially relevant in chemical analysis. The understanding of the phenomenon strongly relies in the study of peroxide models such as 1,2-dioxetanones. In the present contribution, the singlet S2 and the triplet T2 potential energy surfaces of the unimolecular decomposition of 1,2-dioxetanone have been mapped along the O-O and C-C bond coordinates on the grounds of the multiconfigurational CASPT2//CASSCF approach. Results confirm the energy degeneracy between T2, T1, S1, and S0 at the TS region, whereas S2 is unambiguously predicted at higher energies. Triplet-state population is also supported by the spin-orbit couplings between the singlet and triplet states partaking in the process. In particular, the first-principle calculations show that decomposition along the T2 state is a competitive process, having a small (similar to 3 kcal/mol) energy barrier from the ground-state TS structure. The present findings can explain the higher quantum yield of triplet-state population with respect to the excited singlet states recorded experimentally for the uni-molecular decomposition of 1,2-dioxetanone models.

Keyword
Quantum chemistry, Excited states, CASSCF/CASPT2, Chemiluminescence, Dioxetanone decomposition, Triplet states
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-329733 (URN)10.1007/s00214-017-2095-x (DOI)000404250000001 ()
Funder
Swedish Research Council, 2012-3910eSSENCE - An eScience Collaboration
Available from: 2017-09-20 Created: 2017-09-20 Last updated: 2017-12-28Bibliographically approved
Jorner, K., Dreos, A., Emanuelsson, R., El Bakouri, O., Fernández Galván, I., Borjesson, K., . . . Ottosson, H. (2017). Unraveling factors leading to efficient norbornadiene-quadricyclane molecular solar-thermal energy storage systems. Journal of Materials Chemistry A, 5(24), 12369-12378.
Open this publication in new window or tab >>Unraveling factors leading to efficient norbornadiene-quadricyclane molecular solar-thermal energy storage systems
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2017 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 24, 12369-12378 p.Article in journal (Refereed) Published
Abstract [en]

Developing norbornadiene-quadricyclane (NBD-QC) systems for molecular solar-thermal (MOST) energy storage is often a process of trial and error. By studying a series of norbornadienes (NBD-R-2) doubly substituted at the C7-position with R = H, Me, and iPr, we untangle the interrelated factors affecting MOST performance through a combination of experiment and theory. Increasing the steric bulk along the NBD-R-2 series gave higher quantum yields, slightly red-shifted absorptions, and longer thermal lifetimes of the energy-rich QC isomer. However, these advantages are counterbalanced by lower energy storage capacities, and overall R = Me appears most promising for short-term MOST applications. Computationally we find that it is the destabilization of the NBD isomer over the QC isomer with increasing steric bulk that is responsible for most of the observed trends and we can also predict the relative quantum yields by characterizing the S-1/S-0 conical intersections. The significantly increased thermal half-life of NBD-iPr(2) is caused by a higher activation entropy, highlighting a novel strategy to improve thermal half-lives of MOST compounds and other photo-switchable molecules without affecting their electronic properties. The potential of the NBD-R-2 compounds in devices is also explored, demonstrating a solar energy storage efficiency of up to 0.2%. Finally, we show how the insights gained in this study can be used to identify strategies to improve already existing NBD-QC systems.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2017
National Category
Chemical Sciences Engineering and Technology Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-329636 (URN)10.1039/c7ta04259k (DOI)000403664800043 ()
Funder
Swedish Research Council, 2015-04538, 2011-04177, 2012-3910, 2016-03398Knut and Alice Wallenberg FoundationSwedish Foundation for Strategic Research Ragnar Söderbergs stiftelse
Available from: 2017-09-21 Created: 2017-09-21 Last updated: 2017-12-08Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-7567-8295

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