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Santos JL, Janegitz BC, de Oliveira MR, de Souza GL. Exploring the water hydrogen-bonding effects on the ground and low-lying excited states of serotonin. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
In this work, a computational study on the ionization potentials (IPs) of the formaldehyde trimer, (H2CO)3, is presented. Twelve lowest-lying vertical IPs were determined through the use of the coupled-cluster level of theory using correlation consistent basis sets with extrapolation to the complete basis set limit and consideration of core electron correlation effects. Specifically, the equation-of-motion ionization potential coupled-cluster with single and double excitations method with the aug-cc-pVnZ and aug-cc-pCVnZ (n = D and T) basis sets was used. The Feller-Peterson-Dixon (FPD) composite approach was employed to provide accurate IPs, and eight conformations of (H2CO)3 were considered. The FPD IPs determined for (H2CO)3 were found to be systematically lower than those computed for the dimer and monomer of H2CO in the pattern IP(monomer) > IP(dimer) > IP(trimer) for a given IP. In addition, the IPs calculated when considering only the more stable conformation (C0) are in good agreement with those obtained using the eight conformations of the H2CO trimer, and thus, the actual conformation played only a minor role in determining such properties in the present case. By providing first accurate IP results for the H2CO trimer, we hope to motivate future experimental and computational investigations (e.g., studies involving photoionization) that rely on such quantities.
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Affiliation(s)
- Gabriel L C de Souza
- Departamento de Química, Universidade Federal de Mato Grosso, Cuiabá, Mato Grosso 78060-900, Brazil
| | - Kirk A Peterson
- Department of Chemistry, Washington State University, Pullman, Washington 99164, USA
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Falkowski AG, Lima MAP, Kossoski F. Electronic excitation of ethanol by low-energy electron impact. J Chem Phys 2020; 152:244302. [PMID: 32610975 DOI: 10.1063/5.0008428] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report computed differential cross sections (DCSs) for electron impact excitation of the lower-lying states of both trans and gauche tautomers of ethanol, as well as total cross sections for the 15 eV-50 eV energy range. The Schwinger multichannel (SMC) method with pseudopotentials has been employed, and in our most sophisticated calculation in terms of multichannel coupling, 431 open target states have been considered. We found an overall good agreement with the available experimental data at intermediate scattering angles and at higher impact energies. Although we have used a Born-closure scheme for the higher partial waves, we have found discrepancies in the forward direction that were assigned to a poor description of the long-range component of the lower partial waves. Meanwhile, the lack of more Rydberg states could be related to the overestimated DCSs at lower energies. Missing open channels are usually evoked to explain the remaining discrepancies to experiment, but here, we argue that other factors should also be involved. Aiming at an improved description of the target states, we have proposed a simple procedure for selecting the pairs of hole and particle orbitals while keeping the single excitation prescription of the current SMC implementation. A quantitative assessment of the collision process should further consider the individual contribution of each tautomer, which presented quite distinct DCSs in some cases. Our computed excitation energies also support that the second absorption band of ethanol is comprised of three singlet states of each tautomer, rather than the previously suggested two or four states.
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Affiliation(s)
| | - Marco A P Lima
- Instituto de Física "Gleb Wataghin," Universidade Estadual de Campinas, Campinas, Brazil
| | - Fábris Kossoski
- Instituto de Física "Gleb Wataghin," Universidade Estadual de Campinas, Campinas, Brazil
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Affiliation(s)
- Nidhi Sinha
- Atomic and Molecular Physics Lab, Department of Physics, Indian Institute of Technology, Dhanbad, Dhanbad, Jharkhand 826004, India
| | - Bobby Antony
- Atomic and Molecular Physics Lab, Department of Physics, Indian Institute of Technology, Dhanbad, Dhanbad, Jharkhand 826004, India
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Abstract
In the present investigation, the plane-wave Born approximation was employed to calculate the total ionization cross sections by electron impact of methanol, ethanol and 1-propanol from the threshold of ionization to 10 MeV. This method requires continuum generalized oscillator strengths (CGOSs). The two different semi-phenomenological expressions of CGOS, given by Mayol and Salvat and Weizsacker and Williams, along with approximated form of the continuum optical oscillator strength (COOS) by Khare et al. were used. Furthermore, the average of the above two CGOSs was also used. The calculated ionization cross sections were compared to the available previous theoretical results and experimental data. Out of three CGOSs, the present results with the average CGOS were found in good agreement with the available experimental results for all the considered molecules. Collision parameters CRP were also calculated from 0.1 to 100 MeV and the calculations were found to be in excellent agreement with the experimental results of Reike and Prepejchal.
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da Silva DGM, Gomes M, Ghosh S, Silva IFL, Pires WAD, Jones DB, Blanco F, Garcia G, Buckman SJ, Brunger MJ, Lopes MCA. Total cross sections for electron scattering by 1-propanol at impact energies in the range 40-500 eV. J Chem Phys 2017; 147:194307. [PMID: 29166110 DOI: 10.1063/1.5008621] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Absolute total cross section (TCS) measurements for electron scattering from 1-propanol molecules are reported for impact energies from 40 to 500 eV. These measurements were obtained using a new apparatus developed at Juiz de Fora Federal University-Brazil, which is based on the measurement of the attenuation of a collimated electron beam through a gas cell containing the molecules to be studied at a given pressure. Besides these experimental measurements, we have also calculated TCS using the Independent-Atom Model with Screening Corrected Additivity Rule and Interference (IAM-SCAR+I) approach with the level of agreement between them being typically found to be very good.
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Affiliation(s)
- D G M da Silva
- Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG 36936-900, Brazil
| | - M Gomes
- Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG 36936-900, Brazil
| | - S Ghosh
- Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG 36936-900, Brazil
| | - I F L Silva
- Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG 36936-900, Brazil
| | - W A D Pires
- Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG 36936-900, Brazil
| | - D B Jones
- College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
| | - F Blanco
- Departamento de Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - G Garcia
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas (CSIC), Serrano 113-bis, 28006 Madrid, Spain
| | - S J Buckman
- Plasma Research Laboratories, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200, Australia
| | - M J Brunger
- College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
| | - M C A Lopes
- Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG 36936-900, Brazil
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Brunger MJ. Electron scattering and transport in biofuels, biomolecules and biomass fragments. INT REV PHYS CHEM 2017. [DOI: 10.1080/0144235x.2017.1301030] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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