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Scheuermann R, McKenzie I. On the observation of photo-excitation effects in molecules using muon spin spectroscopy. Nat Mater 2022; 21:1108-1109. [PMID: 33972764 DOI: 10.1038/s41563-021-01002-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 04/01/2021] [Indexed: 06/12/2023]
Affiliation(s)
- R Scheuermann
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, Villigen, Switzerland.
| | - I McKenzie
- TRIUMF Center for Molecular and Materials Science, Vancouver, British Columbia, Canada.
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Jingliang M, Wang K, Murahari P, Yokoyama K, Lord JS, Pratt FL, He J, Schulz L, Willis M, Anthony JE, Morley NA, Nuccio L, Misquitta A, Dunstan DJ, Shimomura K, Watanabe I, Zhang S, Heathcote P, Drew AJ. Reply to: On the observation of photo-excitation effects in molecules using muon spin spectroscopy. Nat Mater 2022; 21:1110. [PMID: 33972763 DOI: 10.1038/s41563-021-01003-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 04/01/2021] [Indexed: 06/12/2023]
Affiliation(s)
- M Jingliang
- School of Physics and Astronomy, Queen Mary University of London, London, UK
| | - K Wang
- School of Physics and Astronomy, Queen Mary University of London, London, UK
- College of Physical Sciences and Technology, Sichuan University, Chengdu, People's Republic of China
| | - P Murahari
- School of Physics and Astronomy, Queen Mary University of London, London, UK
| | - K Yokoyama
- School of Physics and Astronomy, Queen Mary University of London, London, UK
- ISIS Muon Facility, Rutherford Appleton Laboratory, Didcot, UK
| | - J S Lord
- ISIS Muon Facility, Rutherford Appleton Laboratory, Didcot, UK
| | - F L Pratt
- ISIS Muon Facility, Rutherford Appleton Laboratory, Didcot, UK
| | - J He
- College of Physical Sciences and Technology, Sichuan University, Chengdu, People's Republic of China
| | - L Schulz
- College of Physical Sciences and Technology, Sichuan University, Chengdu, People's Republic of China
| | - M Willis
- College of Physical Sciences and Technology, Sichuan University, Chengdu, People's Republic of China
| | - J E Anthony
- Department of Chemistry, University of Kentucky, Lexington, KY, USA
| | - N A Morley
- Department of Materials Science and Engineering, University of Sheffield, Sheffield, UK
| | - L Nuccio
- Department of Physics, University of Fribourg, Fribourg, Switzerland
| | - A Misquitta
- School of Physics and Astronomy, Queen Mary University of London, London, UK
| | - D J Dunstan
- School of Physics and Astronomy, Queen Mary University of London, London, UK
| | - K Shimomura
- Materials and Life Science Division, J-PARC Center, Tokai, Japan
| | | | - S Zhang
- College of Physical Sciences and Technology, Sichuan University, Chengdu, People's Republic of China
| | - P Heathcote
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK.
| | - A J Drew
- School of Physics and Astronomy, Queen Mary University of London, London, UK.
- College of Physical Sciences and Technology, Sichuan University, Chengdu, People's Republic of China.
- ISIS Muon Facility, Rutherford Appleton Laboratory, Didcot, UK.
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Dunstan DJ, Crowne J, Drew AJ. Easy computation of the Bayes factor to fully quantify Occam's razor in least-squares fitting and to guide actions. Sci Rep 2022; 12:993. [PMID: 35046427 DOI: 10.1038/s41598-021-04694-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 12/23/2021] [Indexed: 12/12/2022] Open
Abstract
The Bayes factor is the gold-standard figure of merit for comparing fits of models to data, for hypothesis selection and parameter estimation. However, it is little-used because it has been considered to be subjective, and to be computationally very intensive. A simple computational method has been known for at least 30 years, but has been dismissed as an approximation. We show here that all three criticisms are misplaced. The method should be used to complement and augment all least-squares fitting, because it can give very different, and better outcomes than classical methods. It can discriminate between models with equal numbers of parameters and equally good fits to data. It quantifies the Occam’s Razor injunction against over-fitting, and it demands that physically-meaningful parameters rejected by classical significance testing be included in the fitting, to avoid spurious precision and incorrect values for the other parameters. It strongly discourages the use of physically-meaningless parameters, thereby satisfying the Occam’s Razor injunction to use existing entities for explanation rather than multiplying new ones. More generally, as a relative probability, the Bayes factor combines naturally with other quantitative information to guide action in the absence of certain knowledge.
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Goli M, Shahbazian S. Developing effective electronic-only coupled-cluster and Møller-Plesset perturbation theories for the muonic molecules. Phys Chem Chem Phys 2018; 20:16749-16760. [PMID: 29881845 DOI: 10.1039/c8cp02489h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Recently we have proposed an effective Hartree-Fock (EHF) theory for the electrons of the muonic molecules that is formally equivalent to the HF theory within the context of the nuclear-electronic orbital theory [Phys. Chem. Chem. Phys., 2018, 20, 4466]. In the present report we extend the muon-specific effective electronic structure theory beyond the EHF level by introducing the effective second order Møller-Plesset perturbation theory (EMP2) and the effective coupled-cluster theory at single and double excitation levels (ECCSD) as well as an improved version including perturbative triple excitations (ECCSD(T)). These theories incorporate electron-electron correlation into the effective paradigm and through their computational implementation, a diverse set of small muonic species is considered as a benchmark at these post-EHF levels. A comparative computational study on this set demonstrates that the muonic bond length is in general non-negligibly longer than corresponding hydrogenic analogs. Next, the developed post-EHF theories are applied for the muoniated N-heterocyclic carbene/silylene/germylene and the muoniated triazolium cation revealing the relative stability of the sticking sites of the muon in each species. The computational results, in line with previously reported experimental data demonstrate that the muon generally prefers to attach to the divalent atom with carbeneic nature. A detailed comparison of these muonic adducts with the corresponding hydrogenic adducts reveals subtle differences that have already been overlooked.
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Affiliation(s)
- Mohammad Goli
- School of Nano Science, Institute for Research in Fundamental Sciences (IPM), 19395-5531, Tehran, Iran.
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Abstract
A set of effective electronic-only Kohn-Sham (EKS) equations are derived for the muonic molecules (containing a positively charged muon), which are completely equivalent to the coupled electronic-muonic Kohn-Sham equations derived previously within the framework of the nuclear-electronic orbital density functional theory (NEO-DFT). The EKS equations contain effective non-coulombic external potentials depending on parameters describing the muon's vibration, which are optimized during the solution of the EKS equations making the muon's KS orbital reproducible. It is demonstrated that the EKS equations are derivable from a certain class of effective electronic Hamiltonians through applying the usual Hohenberg-Kohn theorems revealing a "duality" between the NEO-DFT and the effective electronic-only DFT methodologies. The EKS equations are computationally applied to a small set of muoniated organic radicals and it is demonstrated that a mean effective potential may be derived for this class of muonic species while an electronic basis set is also designed for the muon. These computational ingredients are then applied to muoniated ferrocenyl radicals, which had been previously detected experimentally through adding a muonium atom to ferrocene. In line with previous computational studies, from the six possible species, the staggered conformer, where the muon is attached to the exo position of the cyclopentadienyl ring, is deduced to be the most stable ferrocenyl radical.
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Affiliation(s)
- Milad Rayka
- Department of Physics and Department of Physical and Computational Chemistry, Shahid Beheshti University, G. C., Evin, P.O. Box 19395-4716, Tehran, 19839, Iran.
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Zhang Z, Zhang Z, Luo Y, Sun S, Zhang G. Spectroscopic and theoretical investigations on intramolecular charge transfer phenomenon in 1-3-dioxolane derivative. Spectrochim Acta A Mol Biomol Spectrosc 2018; 190:324-331. [PMID: 28941886 DOI: 10.1016/j.saa.2017.09.044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 08/26/2017] [Accepted: 09/16/2017] [Indexed: 06/07/2023]
Affiliation(s)
- Zhiyong Zhang
- Laboratory of Heavy Oil Processing, College of Chemical Engineering, China University of Petroleum, Beijing 102249, PR China.
| | - Zhongzhi Zhang
- Laboratory of Heavy Oil Processing, College of Chemical Engineering, China University of Petroleum, Beijing 102249, PR China
| | - Yijing Luo
- Laboratory of Heavy Oil Processing, College of Chemical Engineering, China University of Petroleum, Beijing 102249, PR China
| | - Shanshan Sun
- Laboratory of Heavy Oil Processing, College of Chemical Engineering, China University of Petroleum, Beijing 102249, PR China
| | - Guangqing Zhang
- School of Mechanical, Materials & Mechatronic Engineering, University of Wollongong, Wollongong NSW2522, Australia
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Yokoyama K, Lord JS, Miao J, Murahari P, Drew AJ. Photoexcited Muon Spin Spectroscopy: A New Method for Measuring Excess Carrier Lifetime in Bulk Silicon. Phys Rev Lett 2017; 119:226601. [PMID: 29286821 DOI: 10.1103/physrevlett.119.226601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Indexed: 05/23/2023]
Abstract
We have measured excess carrier lifetime in silicon using photoexcited muon spin spectroscopy. Positive muons implanted deep in a wafer can interact with the optically injected excess carriers and directly probe the bulk carrier lifetime while minimizing the effect from surface recombination. The method is based on the relaxation rate of muon spin asymmetry, which depends on the excess carrier density. The underlying microscopic mechanism has been understood by simulating the four-state muonium model in Si under illumination. We apply the technique to different injection levels and temperatures, and demonstrate its ability for injection- and temperature-dependent lifetime spectroscopy.
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Affiliation(s)
- K Yokoyama
- School of Physics and Astronomy, Queen Mary University of London, Mile End, London E1 4NS, United Kingdom
- ISIS, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - J S Lord
- ISIS, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - J Miao
- School of Physics and Astronomy, Queen Mary University of London, Mile End, London E1 4NS, United Kingdom
- College of Physical Science and Technology, Sichuan University, Chengdu 610064, People's Republic of China
| | - P Murahari
- School of Physics and Astronomy, Queen Mary University of London, Mile End, London E1 4NS, United Kingdom
| | - A J Drew
- School of Physics and Astronomy, Queen Mary University of London, Mile End, London E1 4NS, United Kingdom
- ISIS, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
- College of Physical Science and Technology, Sichuan University, Chengdu 610064, People's Republic of China
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