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Barone V. Quantum chemistry meets high-resolution spectroscopy for characterizing the molecular bricks of life in the gas-phase. Phys Chem Chem Phys 2024; 26:5802-5821. [PMID: 38099409 DOI: 10.1039/d3cp05169b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2024]
Abstract
Computation of accurate geometrical structures and spectroscopic properties of large flexible molecules in the gas-phase is tackled at an affordable cost using a general exploration/exploitation strategy. The most distinctive feature of the approach is the careful selection of different quantum chemical models for energies, geometries and vibrational frequencies with the aim of maximizing the accuracy of the overall description while retaining a reasonable cost for all the steps. In particular, a composite wave-function method is used for energies, whereas a double-hybrid functional (with the addition of core-valence correlation) is employed for geometries and harmonic frequencies and a cheaper hybrid functional for anharmonic contributions. A thorough benchmark based on a wide range of prototypical molecular bricks of life shows that the proposed strategy is close to the accuracy of state-of-the-art composite wave-function methods, and is applicable to much larger systems. A freely available web-utility post-processes the geometries optimized by standard electronic structure codes paving the way toward the accurate yet not prohibitively expensive study of medium- to large-sized molecules by experimentally-oriented researchers.
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Affiliation(s)
- Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy.
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2
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Barone V, Crisci L, Di Grande S. Accurate Thermochemical and Kinetic Parameters at Affordable Cost by Means of the Pisa Composite Scheme (PCS). J Chem Theory Comput 2023; 19:7273-7286. [PMID: 37774410 PMCID: PMC10601482 DOI: 10.1021/acs.jctc.3c00817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Indexed: 10/01/2023]
Abstract
A new strategy for the computation at an affordable cost of geometrical structures, thermochemical parameters, and rate constants for medium-sized molecules in the gas phase is proposed. The most distinctive features of the new model are the systematic use of cc-pVnZ-F12 basis sets, the addition of MP2 core-valence correlation in geometry optimizations by a double-hybrid functional, the separate extrapolation of MP2 and post-MP2 contributions, and the inclusion of anharmonic contributions in zero-point energies and thermodynamic functions. A thorough benchmark based on a wide range of prototypical systems shows that the new scheme outperforms the most well-known model chemistries without the need for any empirical parameter. Additional tests show that the computed zero-point energies and thermal contributions can be confidently used for obtaining accurate thermochemical and kinetic parameters. Since the whole computational workflow is translated in a black-box procedure, which can be followed with standard electronic structure codes, the way is paved for the accurate yet not prohibitively expensive study of medium- to large-sized molecules also by nonspecialists.
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Affiliation(s)
- Vincenzo Barone
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56125 Pisa, Italy
| | - Luigi Crisci
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56125 Pisa, Italy
| | - Silvia Di Grande
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56125 Pisa, Italy
- Scuola
Superiore Meridionale, Largo San Marcellino 10, 80138 Napoli, Italy
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3
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Dzib E, Merino G. The hindered rotor theory: A review. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2022. [DOI: 10.1002/wcms.1583] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Eugenia Dzib
- Departamento de Física Aplicada Centro de Investigación y de Estudios Avanzados Merida Mexico
| | - Gabriel Merino
- Departamento de Física Aplicada Centro de Investigación y de Estudios Avanzados Merida Mexico
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4
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Rath G, Kopp WA, Leonhard K. Coupled Anharmonic Thermochemistry from Stratified Monte Carlo Integration. J Chem Inf Model 2021; 61:5853-5870. [PMID: 34874733 DOI: 10.1021/acs.jcim.1c00668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This study presents configuration integral Monte Carlo integration (CIMCI), a new semiclassical method for handling fully coupled anharmonicity in gas-phase thermodynamics that promises to be black boxable, to be applicable to all kinds of anharmonicity, and to scale better at higher dimensionality than other methods for handling gas-phase molecular anharmonicity. The method does so using automatically and recursively stratified, simultaneous Monte Carlo (MC) integration of multiple functions, following a modified version of the standard MISER scheme that converges at a rate of about the square of naïve MC integration. For the small systems analyzed by this study where proper reference data is available (H2O and H2O2), the method's anharmonic entropy corrections match reference data better than those of other black box anharmonic methods, e.g., vibrational perturbation theory (VPT2) and the McClurg hindered rotor model used with automatic detection of rotors; for H2O2 and NH2OH, the method is also in general agreement with one-dimensional hindered rotor treatments at low temperatures. This holds even when sampling with CIMCI is done with primitive force fields, e.g., UFF, while the competing methods are used with proper, comprehensive potentials, e.g., the M06-2X metahybrid density-functional theory (DFT) functional.
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Affiliation(s)
- Gabriel Rath
- Institute of Technical Thermodynamics, RWTH Aachen University, 52062 Aachen, Germany.,Software for Chemistry & Materials, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Wassja A Kopp
- Institute of Technical Thermodynamics, RWTH Aachen University, 52062 Aachen, Germany
| | - Kai Leonhard
- Institute of Technical Thermodynamics, RWTH Aachen University, 52062 Aachen, Germany
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5
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Barone V, Lupi J, Salta Z, Tasinato N. Development and Validation of a Parameter-Free Model Chemistry for the Computation of Reliable Reaction Rates. J Chem Theory Comput 2021; 17:4913-4928. [PMID: 34228935 PMCID: PMC8359010 DOI: 10.1021/acs.jctc.1c00406] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
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A recently developed
model chemistry (jun-Cheap) has been slightly
modified and proposed as an effective, reliable, and parameter-free
scheme for the computation of accurate reaction rates with special
reference to astrochemical and atmospheric processes. Benchmarks with
different sets of state-of-the-art energy barriers spanning a wide
range of values show that, in the absence of strong multireference
contributions, the proposed model outperforms the most well-known
model chemistries, reaching a subchemical accuracy without any empirical
parameter and with affordable computer times. Some test cases show
that geometries, energy barriers, zero point energies, and thermal
contributions computed at this level can be used in the framework
of the master equation approach based on the ab initio transition-state
theory for obtaining accurate reaction rates.
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Affiliation(s)
- Vincenzo Barone
- SMART Laboratory, Scuola Normale Superiore di Pisa, piazza dei Cavalieri 7, 56125 Pisa, Italy
| | - Jacopo Lupi
- SMART Laboratory, Scuola Normale Superiore di Pisa, piazza dei Cavalieri 7, 56125 Pisa, Italy
| | - Zoi Salta
- SMART Laboratory, Scuola Normale Superiore di Pisa, piazza dei Cavalieri 7, 56125 Pisa, Italy
| | - Nicola Tasinato
- SMART Laboratory, Scuola Normale Superiore di Pisa, piazza dei Cavalieri 7, 56125 Pisa, Italy
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6
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Accurate and general model to predict molar entropy for diatomic molecules. SOUTH AFRICAN JOURNAL OF CHEMICAL ENGINEERING 2020. [DOI: 10.1016/j.sajce.2020.07.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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7
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Berta D, Ferenc D, Bakó I, Madarász Á. Nuclear Quantum Effects from the Analysis of Smoothed Trajectories: Pilot Study for Water. J Chem Theory Comput 2020; 16:3316-3334. [PMID: 32268067 PMCID: PMC7304866 DOI: 10.1021/acs.jctc.9b00703] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
![]()
Nuclear quantum effects
have significant contributions to thermodynamic
quantities and structural properties; furthermore, very expensive
methods are necessary for their accurate computation. In most calculations,
these effects, for instance, zero-point energies, are simply neglected
or only taken into account within the quantum harmonic oscillator
approximation. Herein, we present a new method, Generalized Smoothed
Trajectory Analysis, to determine nuclear quantum effects from molecular
dynamics simulations. The broad applicability is demonstrated with
the examples of a harmonic oscillator and different states of water.
Ab initio molecular dynamics simulations have been performed for ideal
gas up to the temperature of 5000 K. Classical molecular dynamics
have been carried out for hexagonal ice, liquid water, and vapor at
atmospheric pressure. With respect to the experimental heat capacity,
our method outperforms previous calculations in the literature in
a wide temperature range at lower computational cost than other alternatives.
Dynamic and structural nuclear quantum effects of water are also discussed.
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Affiliation(s)
- Dénes Berta
- Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok Körútja 2, H-1117 Budapest, Hungary.,Department of Chemistry, Kings College London, 7 Trinity Street, SE1 1DB London, United Kingdom
| | - Dávid Ferenc
- Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok Körútja 2, H-1117 Budapest, Hungary
| | - Imre Bakó
- Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok Körútja 2, H-1117 Budapest, Hungary
| | - Ádám Madarász
- Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok Körútja 2, H-1117 Budapest, Hungary
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9
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A never-ending story in the sky: The secrets of chemical evolution. Phys Life Rev 2020; 32:59-94. [DOI: 10.1016/j.plrev.2019.07.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 06/26/2019] [Accepted: 07/02/2019] [Indexed: 01/13/2023]
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10
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Jasper AW, Harding LB, Knight C, Georgievskii Y. Anharmonic Rovibrational Partition Functions at High Temperatures: Tests of Reduced-Dimensional Models for Systems with up to Three Fluxional Modes. J Phys Chem A 2019; 123:6210-6228. [DOI: 10.1021/acs.jpca.9b03592] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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11
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Puzzarini C, Bloino J, Tasinato N, Barone V. Accuracy and Interpretability: The Devil and the Holy Grail. New Routes across Old Boundaries in Computational Spectroscopy. Chem Rev 2019; 119:8131-8191. [DOI: 10.1021/acs.chemrev.9b00007] [Citation(s) in RCA: 114] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Cristina Puzzarini
- Dipartimento di Chimica “Giacomo Ciamician”, Università di Bologna, Via F. Selmi 2, I-40126 Bologna, Italy
| | - Julien Bloino
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
| | - Nicola Tasinato
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
| | - Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
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12
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Aieta C, Gabas F, Ceotto M. Parallel Implementation of Semiclassical Transition State Theory. J Chem Theory Comput 2019; 15:2142-2153. [PMID: 30822385 DOI: 10.1021/acs.jctc.8b01286] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper presents the parsctst code, an efficient parallel implementation of the semiclassical transition state theory (SCTST) for reaction rate constant calculations. Parsctst is developed starting from a previously presented approach for the computation of the vibrational density of states of fully coupled anharmonic molecules ( Nguyen et al. Chem. Phys. Lett. 2010 , 499 , 915 ). The parallel implementation makes it practical to tackle reactions involving more than 100 fully coupled anharmonic vibrational degrees of freedom and also includes multidimensional tunneling effects. After describing the pseudocode and demonstrating its computational efficiency, we apply the new code for estimating the rate constant of the proton transfer isomerization reaction of the 2,4,6-tri- tert-butylphenyl to 3,5-di- tert-butylneophyl. Comparison with both theoretical and experimental results is presented. Parsctst code is user-friendly and provides a significant computational time saving compared to serial calculations. We believe that parsctst can boost the application of SCTST as an alternative to the basic transition state theory for accurate kinetics modeling not only in combustion or atmospheric chemistry, but also in organic synthesis, where bigger reactive systems are encountered.
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Affiliation(s)
- Chiara Aieta
- Dipartimento di Chimica , Università degli Studi di Milano , via C. Golgi 19 , 20133 Milano , Italy
| | - Fabio Gabas
- Dipartimento di Chimica , Università degli Studi di Milano , via C. Golgi 19 , 20133 Milano , Italy
| | - Michele Ceotto
- Dipartimento di Chimica , Università degli Studi di Milano , via C. Golgi 19 , 20133 Milano , Italy
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13
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Jasper AW, Gruey ZB, Harding LB, Georgievskii Y, Klippenstein SJ, Wagner AF. Anharmonic Rovibrational Partition Functions for Fluxional Species at High Temperatures via Monte Carlo Phase Space Integrals. J Phys Chem A 2018; 122:1727-1740. [DOI: 10.1021/acs.jpca.7b11722] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ahren W. Jasper
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Zackery B. Gruey
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Lawrence B. Harding
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Yuri Georgievskii
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Stephen J. Klippenstein
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Albert F. Wagner
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
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14
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Jia CS, Wang CW, Zhang LH, Peng XL, Tang HM, Liu JY, Xiong Y, Zeng R. Predictions of entropy for diatomic molecules and gaseous substances. Chem Phys Lett 2018. [DOI: 10.1016/j.cplett.2017.12.013] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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15
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Piserchia A, Banerjee S, Barone V. General Approach to Coupled Reactive Smoluchowski Equations: Integration and Application of Discrete Variable Representation and Generalized Coordinate Methods to Diffusive Problems. J Chem Theory Comput 2017; 13:5900-5910. [PMID: 29091430 DOI: 10.1021/acs.jctc.7b00685] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A new and more general approach to diffusion problems with the inclusion of reactivity among different coupled diffusional states is rationalized and presented. The integration of our previous developments in such a field [Phys. Chem. Chem. Phys., 2015, 17, 17362-17374; J. Chem. Theory Comput., 2016, 12, 3482-3490] are implemented in a software package tool allowing the generic user to set up and run diffusional calculations with very low efforts. We show the applicability of the whole framework to a generic diffusional case of chemical interest that is the study case of (N,N-dimethylamino)benzonitrile (DMABN) fluorescence, whose excited state undergoes twisted intramolecular charge transfer (TICT) relaxation. The population dynamics of the excited state coupled to the ground state is followed, and a fluorescence decay spectrum is calculated. The theoretical and numerical background here presented is robust and general enough to complement a wide number of diffusional problems of current interest.
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Affiliation(s)
- Andrea Piserchia
- Scuola Normale Superiore , piazza dei Cavalieri 7, I-56126 Pisa, Italy
| | | | - Vincenzo Barone
- Scuola Normale Superiore , piazza dei Cavalieri 7, I-56126 Pisa, Italy
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16
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Biczysko M, Bloino J, Puzzarini C. Computational challenges in Astrochemistry. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2017. [DOI: 10.1002/wcms.1349] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Malgorzata Biczysko
- International Center for Quantum and Molecular Structures, College of SciencesShanghai University Shanghai China
| | - Julien Bloino
- Consiglio Nazionale delle Ricerche, Istituto di Chimica dei Composti OrganoMetalliciUOS di Pisa, Area della Ricerca CNR Pisa Italy
- Scuola Normale Superiore Classe di Scienze, Pisa Italy
| | - Cristina Puzzarini
- Department of Chemistry “Giacomo Ciamician”University of Bologna Bologna Italy
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17
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Williams-Noonan BJ, Yuriev E, Chalmers DK. Free Energy Methods in Drug Design: Prospects of “Alchemical Perturbation” in Medicinal Chemistry. J Med Chem 2017; 61:638-649. [DOI: 10.1021/acs.jmedchem.7b00681] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Billy J. Williams-Noonan
- Medicinal Chemistry, Monash
Institute of Pharmaceutical Sciences, Monash University, 381 Royal
Parade, Parkville, Victoria 3052, Australia
| | - Elizabeth Yuriev
- Medicinal Chemistry, Monash
Institute of Pharmaceutical Sciences, Monash University, 381 Royal
Parade, Parkville, Victoria 3052, Australia
| | - David K. Chalmers
- Medicinal Chemistry, Monash
Institute of Pharmaceutical Sciences, Monash University, 381 Royal
Parade, Parkville, Victoria 3052, Australia
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18
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Bulik IW, Frisch MJ, Vaccaro PH. Vibrational self-consistent field theory using optimized curvilinear coordinates. J Chem Phys 2017; 147:044110. [DOI: 10.1063/1.4995440] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ireneusz W. Bulik
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, USA
| | - Michael J. Frisch
- Gaussian, Inc., 340 Quinnipiac St. Bldg. 40, Wallingford, Connecticut 06492, USA
| | - Patrick H. Vaccaro
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, USA
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19
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Jia CS, Wang CW, Zhang LH, Peng XL, Zeng R, You XT. Partition function of improved Tietz oscillators. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.03.068] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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22
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Vazart F, Calderini D, Puzzarini C, Skouteris D, Barone V. State-of-the-Art Thermochemical and Kinetic Computations for Astrochemical Complex Organic Molecules: Formamide Formation in Cold Interstellar Clouds as a Case Study. J Chem Theory Comput 2016; 12:5385-5397. [PMID: 27689448 PMCID: PMC5856337 DOI: 10.1021/acs.jctc.6b00379] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We describe an integrated computational strategy aimed at providing reliable thermochemical and kinetic information on the formation processes of astrochemical complex organic molecules. The approach involves state-of-the-art quantum-mechanical computations, second-order vibrational perturbation theory, and kinetic models based on capture and transition state theory together with the master equation approach. Notably, tunneling, quantum reflection, and leading anharmonic contributions are accounted for in our model. Formamide has been selected as a case study in view of its interest as a precursor in the abiotic amino acid synthesis. After validation of the level of theory chosen for describing the potential energy surface, we have investigated several pathways of the OH + CH2NH and NH2 + H2CO reaction channels. Our results show that both reaction channels are essentially barrierless (in the sense that all relevant transition states lie below or only marginally above the reactants) and once tunneling is taken into the proper account indicate that the reaction can occur under the low temperature conditions of interstellar environments.
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Affiliation(s)
- Fanny Vazart
- Scuola Normale Superiore, piazza dei Cavalieri 7, 56125 Pisa, Italy
| | - Danilo Calderini
- Scuola Normale Superiore, piazza dei Cavalieri 7, 56125 Pisa, Italy
| | - Cristina Puzzarini
- Dipartimento di Chimica "Giacomo Ciamician", Via F. Selmi 2, 40126 Bologna, Italy
| | | | - Vincenzo Barone
- Scuola Normale Superiore, piazza dei Cavalieri 7, 56125 Pisa, Italy
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23
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Piserchia A, Barone V. Toward a General Yet Effective Computational Approach for Diffusive Problems: Variable Diffusion Tensor and DVR Solution of the Smoluchowski Equation along a General One-Dimensional Coordinate. J Chem Theory Comput 2016; 12:3482-90. [PMID: 27403666 DOI: 10.1021/acs.jctc.6b00388] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A generalization to arbitrary large amplitude motions of a recent approach to the evaluation of diffusion tensors [ J. Comput. Chem. , 2009 , 30 , 2 - 13 ] is presented and implemented in a widely available package for electronic structure computations. A fully black-box tool is obtained, which, starting from the generation of geometric structures along different kinds of paths, proceeds toward the evaluation of an effective diffusion tensor and to the solution of one-dimensional Smoluchowski equations by a robust numerical approach rooted in the discrete variable representation (DVR). Application to a number of case studies shows that the results issuing from our approach are identical to those delivered by previous software (in particular DiTe) for rigid scans along a dihedral angle, but can be improved by employing relaxed scans (i.e., constrained geometry optimizations) or even more general large amplitude paths. The theoretical and numerical background is robust and general enough to allow quite straightforward extensions in several directions (e.g., inclusion of reactive paths, solution of Fokker-Planck or stochastic Liouville equations, multidimensional problems, free-energy rather than electronic-energy driven processes).
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Affiliation(s)
- Andrea Piserchia
- Scuola Normale Superiore, piazza dei Cavalieri 7, I-56126 Pisa, Italy
| | - Vincenzo Barone
- Scuola Normale Superiore, piazza dei Cavalieri 7, I-56126 Pisa, Italy
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24
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Ferreira da Cunha T, Calderini D, Skouteris D. Analysis of Partition Functions for Metallocenes: Ferrocene, Ruthenocene, and Osmocene. J Phys Chem A 2016; 120:5282-7. [PMID: 27003631 DOI: 10.1021/acs.jpca.6b01280] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present a calculation of the torsional potential of the three metallocenes of the iron group, that is, ferrocene, ruthenocene, and osmocene, calculated with the GAUSSIAN program suite. Both a variational method (through computation of the exact energy levels) and our Chebyshev imaginary time propagation method are used to calculate the hindered rotation partition function, demonstrating the efficiency of the Chebyshev scheme. The transition from a semirigid through a hindered rotor to the free rotor regime is demonstrated, and the effect of the hindered rotation (as opposed to a harmonic) treatment on the thermodynamics of metallocenes is demonstrated.
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Affiliation(s)
| | - D Calderini
- Scuola Normale Superiore , Piazza dei Cavalieri 7, Pisa 56126, Italy.,Istituto Nazionale di Fisica Nucleare (INFN) sezione di Pisa , Largo Bruno Pontecorvo 3, 56127, Pisa, Italy
| | - D Skouteris
- Scuola Normale Superiore , Piazza dei Cavalieri 7, Pisa 56126, Italy
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