1
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Tom R, Gao S, Yang Y, Zhao K, Bier I, Buchanan EA, Zaykov A, Havlas Z, Michl J, Marom N. Inverse Design of Tetracene Polymorphs with Enhanced Singlet Fission Performance by Property-Based Genetic Algorithm Optimization. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2023; 35:1373-1386. [PMID: 36999121 PMCID: PMC10042130 DOI: 10.1021/acs.chemmater.2c03444] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 01/06/2023] [Indexed: 06/19/2023]
Abstract
The efficiency of solar cells may be improved by using singlet fission (SF), in which one singlet exciton splits into two triplet excitons. SF occurs in molecular crystals. A molecule may crystallize in more than one form, a phenomenon known as polymorphism. Crystal structure may affect SF performance. In the common form of tetracene, SF is experimentally known to be slightly endoergic. A second, metastable polymorph of tetracene has been found to exhibit better SF performance. Here, we conduct inverse design of the crystal packing of tetracene using a genetic algorithm (GA) with a fitness function tailored to simultaneously optimize the SF rate and the lattice energy. The property-based GA successfully generates more structures predicted to have higher SF rates and provides insight into packing motifs associated with improved SF performance. We find a putative polymorph predicted to have superior SF performance to the two forms of tetracene, whose structures have been determined experimentally. The putative structure has a lattice energy within 1.5 kJ/mol of the most stable common form of tetracene.
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Affiliation(s)
- Rithwik Tom
- Department
of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania15213, United States
| | - Siyu Gao
- Department
of Materials Science and Engineering, Carnegie
Mellon University, Pittsburgh, Pennsylvania15213, United States
| | - Yi Yang
- Department
of Materials Science and Engineering, Carnegie
Mellon University, Pittsburgh, Pennsylvania15213, United States
| | - Kaiji Zhao
- Department
of Materials Science and Engineering, Carnegie
Mellon University, Pittsburgh, Pennsylvania15213, United States
| | - Imanuel Bier
- Department
of Materials Science and Engineering, Carnegie
Mellon University, Pittsburgh, Pennsylvania15213, United States
| | - Eric A. Buchanan
- Department
of Chemistry, University of Colorado, Boulder, Colorado80309, United States
| | - Alexandr Zaykov
- Institute
of Organic Chemistry and Biochemistry, Czech
Academy of Sciences, 16610Prague 6, Czech
Republic
- Department
of Physical Chemistry, University of Chemistry
and Technology, 166 28Prague 6, Czech Republic
| | - Zdeněk Havlas
- Institute
of Organic Chemistry and Biochemistry, Czech
Academy of Sciences, 16610Prague 6, Czech
Republic
| | - Josef Michl
- Department
of Chemistry, University of Colorado, Boulder, Colorado80309, United States
- Institute
of Organic Chemistry and Biochemistry, Czech
Academy of Sciences, 16610Prague 6, Czech
Republic
| | - Noa Marom
- Department
of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania15213, United States
- Department
of Materials Science and Engineering, Carnegie
Mellon University, Pittsburgh, Pennsylvania15213, United States
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania15213, United States
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2
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Walia R, Yang J. Exploring optimal multimode vibronic pathways in singlet fission of azaborine analogues of perylene. Photochem Photobiol Sci 2022; 21:1689-1700. [PMID: 35716333 DOI: 10.1007/s43630-022-00251-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 05/23/2022] [Indexed: 10/18/2022]
Abstract
The development of new singlet fission chromophores is a vibrant area of research to explore the possibility of efficient photovoltaic devices. Using high-level ab-initio density matrix renormalization group calculations, we present a systematic analysis of BN-doped perylenes for their potential application as singlet fission candidates. Four singlet fission chromophores are identified considering the monomer-based properties and their excitonic characters are further analyzed in a dimer configuration optimized in a six-dimensional space for local maxima of fission rates. Furthermore, a multistate multimode vibronic Hamiltonian is employed to identify intra- and interstate vibrational pathways for excitation energy modulation. Several photophysical properties such as Davydov splitting, activation energy and vibronic admixture of multiexcitonic and charge-transfer states are calculated for physically accessible dimers. The optimal dimer packing results in appropriate vibrational relaxation of singlet fission states and promotes significant population transfer which would be more attenuated without such couplings. This work not only identifies potential singlet fission systems with favorable electronic properties but also highlights the sensitivity of dimer packings with respect to the substitution patterns in singlet fission chromophores.
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Affiliation(s)
- Rajat Walia
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
| | - Jun Yang
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China.
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3
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Pensack RD, Purdum GE, Mazza SM, Grieco C, Asbury JB, Anthony JE, Loo YL, Scholes GD. Excited-State Dynamics of 5,14- vs 6,13-Bis(trialkylsilylethynyl)-Substituted Pentacenes: Implications for Singlet Fission. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:9784-9793. [PMID: 35756579 PMCID: PMC9210346 DOI: 10.1021/acs.jpcc.2c00897] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 05/20/2022] [Indexed: 05/16/2023]
Abstract
Singlet fission is a process in conjugated organic materials that has the potential to considerably improve the performance of devices in many applications, including solar energy conversion. In any application involving singlet fission, efficient triplet harvesting is essential. At present, not much is known about molecular packing arrangements detrimental to singlet fission. In this work, we report a molecular packing arrangement in crystalline films of 5,14-bis(triisopropylsilylethynyl)-substituted pentacene, specifically a local (pairwise) packing arrangement, responsible for complete quenching of triplet pairs generated via singlet fission. We first demonstrate that the energetic condition necessary for singlet fission is satisfied in amorphous films of the 5,14-substituted pentacene derivative. However, while triplet pairs form highly efficiently in the amorphous films, only a modest yield of independent triplets is observed. In crystalline films, triplet pairs also form highly efficiently, although independent triplets are not observed because triplet pairs decay rapidly and are quenched completely. We assign the quenching to a rapid nonadiabatic transition directly to the ground state. Detrimental quenching is observed in crystalline films of two additional 5,14-bis(trialkylsilylethynyl)-substituted pentacenes with either ethyl or isobutyl substituents. Developing a better understanding of the losses identified in this work, and associated molecular packing, may benefit overcoming losses in solids of other singlet fission materials.
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Affiliation(s)
- Ryan D. Pensack
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Geoffrey E. Purdum
- Department
of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Samuel M. Mazza
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Christopher Grieco
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - John B. Asbury
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - John E. Anthony
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Yueh-Lin Loo
- Department
of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
- Andlinger
Center for Energy and the Environment, Princeton
University, Princeton, New Jersey 08544, United States
| | - Gregory D. Scholes
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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4
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Aguilar Suarez LE, de Graaf C, Faraji S. Influence of the crystal packing in singlet fission: one step beyond the gas phase approximation. Phys Chem Chem Phys 2021; 23:14164-14177. [PMID: 33988190 PMCID: PMC8284770 DOI: 10.1039/d1cp00298h] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Singlet fission (SF), a multiexciton generation process, has been proposed as an alternative to enhance the performance of solar cells. The gas phase dimer model has shown its utility to study this process, but it does not always cover all the physics and the effect of the surrounding atoms has to be included in such cases. In this contribution, we explore the influence of crystal packing on the electronic couplings, and on the so-called exciton descriptors and electron–hole correlation plots. We have studied three tetracene dimers extracted from the crystal structure, as well as several dimers and trimers of the α and β polymorphs of 1,3-diphenylisobenzofuran (DPBF). These polymorphs show different SF yields. Our results highlight that the character of the excited states of tetracene depends on both the mutual disposition of molecules and inclusion of the environment. The latter does however not change significantly the interpretation of the SF mechanism in the studied systems. For DPBF, we establish how the excited state analysis is able to pinpoint differences between the polymorphs. We observe strongly bound correlated excitons in the β polymorph which might hinder the formation of the 1TT state and, consequently, explain its low SF yield. Singlet fission (SF), a multiexciton generation process, has been proposed as an alternative to enhance the performance of solar cells.![]()
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Affiliation(s)
- Luis Enrique Aguilar Suarez
- Theoretical Chemistry Group, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
| | - Coen de Graaf
- Theoretical Chemistry Group, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands. and Department of Physical and Inorganic Chemistry, Universitat Rovira i Virgili, Campus Sescelades, C. Marcel lí Domingo 1, 43007 Tarragona, Spain and ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Shirin Faraji
- Theoretical Chemistry Group, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
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5
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Tonami T, Sugimori R, Sakai R, Tokuyama K, Miyamoto H, Nakano M. Theoretical study on the effect of applying an external static electric field on the singlet fission dynamics of pentacene dimer models. Phys Chem Chem Phys 2021; 23:11624-11634. [PMID: 33955433 DOI: 10.1039/d1cp00880c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigate the effect of applying an external static electric field on the singlet fission (SF) dynamics of pentacene dimer models using quantum chemical calculations and exciton dynamics simulations. It is found that the excitation energies of anion-cation (AC) and cation-anion (CA) pair exciton states in the SF process are significantly stabilized and destabilized, respectively, by applying an external static electric field (F) in the intermolecular direction. As a result, this change of excitation energies is found to accelerate the SF dynamics in pentacene dimer models. In particular, in the tilted- and parallel-type pentacene dimer models, SF rates at F = 0.001 a.u. are predicted to be about 2.3 and 3.0 times as large as those at F = 0.0 a.u. while keeping the TT yields large. The present result contributes to paving the way for novel physical and chemical controls, that is, an external static electric field application and donor/acceptor substitution on SF molecules, of SF dynamics.
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Affiliation(s)
- Takayoshi Tonami
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Ryota Sugimori
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Ryota Sakai
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Kazuaki Tokuyama
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Hajime Miyamoto
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Masayoshi Nakano
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan. and Center for Spintronics Research Network (CSRN), Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan and Center for Quantum Information and Quantum Biology (QIQB), International Advanced Research Institute (IARI), Osaka University, Toyonaka, Osaka 560-8531, Japan and Innovative Catalysis Science Division (ICS), Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Toyonaka, Osaka 560-8531, Japan and Research Center for Solar Energy Chemistry (RCSEC), Division of Quantum Photochemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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6
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Accomasso D, Granucci G, Wibowo M, Persico M. Delocalization effects in singlet fission: Comparing models with two and three interacting molecules. J Chem Phys 2020; 152:244125. [PMID: 32610952 DOI: 10.1063/5.0009914] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present surface hopping simulations of singlet fission in 2,5-bis(fluorene-9-ylidene)-2,5-dihydrothiophene (ThBF). In particular, we performed simulations based on quantum mechanics/molecular mechanics (QM/MM) schemes in which either two or three ThBF molecules are inserted in the QM region and embedded in their MM crystal environment. Our aim was to investigate the changes in the photodynamics that are brought about by extending the delocalization of the excited states beyond the minimal model of a dimer. In the simulations based on the trimer model, compared to the dimer-based ones, we observed a faster time evolution of the state populations, with the largest differences associated with both the rise and decay times for the intermediate charge transfer states. Moreover, for the trimer, we predicted a singlet fission quantum yield of ∼204%, which is larger than both the one extracted for the dimer (∼179%) and the theoretical upper limit of 200% for the dimer-based model of singlet fission. Although our study cannot account for the effects of extending the delocalization beyond three molecules, our findings clearly indicate how and why the singlet fission dynamics can be affected.
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Affiliation(s)
- Davide Accomasso
- Università di Pisa, Dipartimento di Chimica e Chimica Industriale, via G. Moruzzi 13, 56124 Pisa, Italy
| | - Giovanni Granucci
- Università di Pisa, Dipartimento di Chimica e Chimica Industriale, via G. Moruzzi 13, 56124 Pisa, Italy
| | - Meilani Wibowo
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Maurizio Persico
- Università di Pisa, Dipartimento di Chimica e Chimica Industriale, via G. Moruzzi 13, 56124 Pisa, Italy
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7
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The Photophysical Properties of Triisopropylsilyl-ethynylpentacene—A Molecule with an Unusually Large Singlet-Triplet Energy Gap—In Solution and Solid Phases. CHEMISTRY-SWITZERLAND 2020. [DOI: 10.3390/chemistry2020033] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The process of singlet-exciton fission (SEF) has attracted much attention of late. One of the most popular SEF compounds is TIPS-pentacene (TIPS-P, where TIPS = triisopropylsilylethynyl) but, despite its extensive use as both a reference and building block, its photophysical properties are not so well established. In particular, the triplet state excitation energy remains uncertain. Here, we report quantitative data and spectral characterization for excited-singlet and -triplet states in dilute solution. The triplet energy is determined to be 7940 ± 1200 cm−1 on the basis of sensitization studies using time-resolved photoacoustic calorimetry. The triplet quantum yield at the limit of low concentration and low laser intensity is only ca. 1%. Self-quenching occurs at high solute concentration where the fluorescence yield and lifetime decrease markedly relative to dilute solution but we were unable to detect excimer emission by steady-state spectroscopy. Short-lived fluorescence, free from excimer emission or phosphorescence, occurs for crystals of TIPS-P, most likely from amorphous domains.
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8
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Korovina NV, Pompetti NF, Johnson JC. Lessons from intramolecular singlet fission with covalently bound chromophores. J Chem Phys 2020; 152:040904. [PMID: 32007061 DOI: 10.1063/1.5135307] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Molecular dimers, oligomers, and polymers are versatile components in photophysical and optoelectronic architectures that could impact a variety of applications. We present a perspective on such systems in the field of singlet fission, which effectively multiplies excitons and produces a unique excited state species, the triplet pair. The choice of chromophore and the nature of the attachment between units, both geometrical and chemical, play a defining role in the dynamical scheme that evolves upon photoexcitation. Specific final outcomes (e.g., separated and uncorrelated triplet pairs) are being sought through rational design of covalently bound chromophore architectures built with guidance from recent fundamental studies that correlate structure with excited state population flow kinetics.
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Affiliation(s)
- Nadezhda V Korovina
- National Renewable Energy Laboratory, 15013 Denver West Pkwy, Golden, Colorado 80401, USA
| | - Nicholas F Pompetti
- National Renewable Energy Laboratory, 15013 Denver West Pkwy, Golden, Colorado 80401, USA
| | - Justin C Johnson
- National Renewable Energy Laboratory, 15013 Denver West Pkwy, Golden, Colorado 80401, USA
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9
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Ryerson JL, Zaykov A, Aguilar Suarez LE, Havenith RWA, Stepp BR, Dron PI, Kaleta J, Akdag A, Teat SJ, Magnera TF, Miller JR, Havlas Z, Broer R, Faraji S, Michl J, Johnson JC. Structure and photophysics of indigoids for singlet fission: Cibalackrot. J Chem Phys 2019; 151:184903. [PMID: 31731849 DOI: 10.1063/1.5121863] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We report an investigation of structure and photophysics of thin layers of cibalackrot, a sturdy dye derived from indigo by double annulation at the central double bond. Evaporated layers contain up to three phases, two crystalline and one amorphous. Relative amounts of all three have been determined by a combination of X-ray diffraction and FT-IR reflectance spectroscopy. Initially, excited singlet state rapidly produces a high yield of a transient intermediate whose spectral properties are compatible with charge-transfer nature. This intermediate more slowly converts to a significant yield of triplet, which, however, does not exceed 100% and may well be produced by intersystem crossing rather than singlet fission. The yields were determined by transient absorption spectroscopy and corrected for effects of partial sample alignment by a simple generally applicable procedure. Formation of excimers was also observed. In order to obtain guidance for improving molecular packing by a minor structural modification, calculations by a simplified frontier orbital method were used to find all local maxima of singlet fission rate as a function of geometry of a molecular pair. The method was tested at 48 maxima by comparison with the ab initio Frenkel-Davydov exciton model.
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Affiliation(s)
- Joseph L Ryerson
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, USA
| | - Alexandr Zaykov
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
| | - Luis E Aguilar Suarez
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Remco W A Havenith
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Brian R Stepp
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, USA
| | - Paul I Dron
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, USA
| | - Jiří Kaleta
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
| | - Akin Akdag
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, USA
| | - Simon J Teat
- Advanced Light Source, Lawrence Berkeley National Lab, 1 Cyclotron Rd., Berkeley, California 94720, USA
| | - Thomas F Magnera
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, USA
| | - John R Miller
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Zdeněk Havlas
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
| | - Ria Broer
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Shirin Faraji
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Josef Michl
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, USA
| | - Justin C Johnson
- National Renewable Energy Laboratory, Golden, Colorado 80401, USA
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10
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Zaykov A, Felkel P, Buchanan EA, Jovanovic M, Havenith RWA, Kathir RK, Broer R, Havlas Z, Michl J. Singlet Fission Rate: Optimized Packing of a Molecular Pair. Ethylene as a Model. J Am Chem Soc 2019; 141:17729-17743. [PMID: 31509712 DOI: 10.1021/jacs.9b08173] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
A procedure is described for unbiased identification of all π-electron chromophore pair geometry choices that locally maximize the rate of conversion of a singlet exciton into a singlet biexciton (triplet pair), using a simplified version of the diabatic frontier orbital model of singlet fission (SF). The resulting approximate optimal geometries provide insight and are expected to represent useful starting points for searches by more advanced methods. The general procedure is illustrated on a pair of ethylenes as the simplest model of a π-electron system, but it is applicable to pairs of much larger molecules, with dozens of non-hydrogen atoms, and not necessarily planar. We first examine the value of |TA|2, the square of the electronic matrix element for SF with initial excitation fully localized on partner A, on a grid of several billion geometries within the six-dimensional space of physically realizable possibilities. Several of the optimized pair geometries are somewhat unexpected, but all are found to follow the qualitative guidance proposed earlier. In the neighborhood of each local maximum of |TA|2, consideration of mixing with charge-transfer configurations and of excitonic interaction between partners A and B determines the SF energy balance and yields squared matrix elements |T*|2 and |T**|2 for the lower and upper excitonic states S* and S**, respectively. Assuming Boltzmann populations of these states, the geometry is further optimized to maximize k, the sum of the SF rates obtained from Marcus theory, and this reorders the suitable geometries substantially. At 87 pair geometries, the |T*|2 and |T**|2 values are compared with those obtained from high-level ab initio nonorthogonal configuration interaction calculations and found to follow the same trend. Finally, the biexciton binding energy at the optimized geometries is calculated. Altogether, 13 significant local maxima of SF rate for a pair of ethylenes are identified in the physically relevant part of space that avoids molecular interpenetration in the hard-sphere approximation. The three best geometries are twist-stacked, slip-stacked, and L-shaped. The maxima occur at the (five-dimensional) surfaces of seven six-dimensional "parent" regions of space centered at physically inaccessible geometries at which the calculated SF rate is very large but the two ethylenes interpenetrate. The results are displayed in interactive graphics. The computer code ("Simple") written for these calculations is flexible in that it permits a choice of performing the search for local maxima in six dimensions on |TA|2, |T*|2, or k. It is available as freeware at https://cloud.uochb.cas.cz/simple .
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Affiliation(s)
- Alexandr Zaykov
- Institute of Organic Chemistry and Biochemistry , Czech Academy of Sciences , 16610 Prague 6, Czech Republic.,Department of Physical Chemistry , University of Chemistry and Technology , 16628 Prague 6, Czech Republic
| | - Petr Felkel
- Faculty of Electrical Engineering , Czech Technical University in Prague , 16627 Prague 6, Czech Republic
| | - Eric A Buchanan
- Department of Chemistry , University of Colorado , Boulder , Colorado 80309-0215 , United States
| | - Milena Jovanovic
- Department of Chemistry , University of Colorado , Boulder , Colorado 80309-0215 , United States
| | - Remco W A Havenith
- Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 4, 9747 AG Groningen , The Netherlands.,Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 4, 9747 AG Groningen , The Netherlands.,Department of Inorganic and Physical Chemistry , Ghent University , Krijgslaan 281 (S3) , B-9000 Gent , Belgium
| | - R K Kathir
- Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 4, 9747 AG Groningen , The Netherlands
| | - Ria Broer
- Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 4, 9747 AG Groningen , The Netherlands
| | - Zdeněk Havlas
- Institute of Organic Chemistry and Biochemistry , Czech Academy of Sciences , 16610 Prague 6, Czech Republic
| | - Josef Michl
- Institute of Organic Chemistry and Biochemistry , Czech Academy of Sciences , 16610 Prague 6, Czech Republic.,Department of Chemistry , University of Colorado , Boulder , Colorado 80309-0215 , United States
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