Electronic spectrum and characterization of diabatic potential energy surfaces for thiophenol

2018 ◽  
Vol 20 (44) ◽  
pp. 28144-28154 ◽  
Author(s):  
Linyao Zhang ◽  
Donald G. Truhlar ◽  
Shaozeng Sun
Keyword(s):  
Potential Energy ◽  
Electronic Spectrum ◽  
Potential Energy Surfaces ◽  
Uv Spectrum ◽  
Potential Surfaces ◽  
Energy Surfaces

We present an accurate simulation of the UV spectrum and a diabatization of three singlet potential surfaces along four coordinates.

scholarly journals Correction: Electronic spectrum and characterization of diabatic potential energy surfaces for thiophenol

2019 ◽  
Vol 21 (15) ◽  
pp. 8179-8179
Author(s):  
Linyao Zhang ◽  
Donald G. Truhlar ◽  
Shaozeng Sun
Keyword(s):  
Potential Energy ◽  
Electronic Spectrum ◽  
Potential Energy Surfaces ◽  
Chem Phys ◽  
Energy Surfaces ◽  
Phys Chem Chem Phys

Correction for ‘Electronic spectrum and characterization of diabatic potential energy surfaces for thiophenol’ by Linyao Zhang et al., Phys. Chem. Chem. Phys., 2018, 20, 28144–28154.

Empirical Potential-Energy Surfaces Fitting Using Feed forward Neural Networks

2012 ◽  
Author(s):  
Lionel Raff ◽  
Ranga Komanduri ◽  
Martin Hagan ◽  
Satish Bukkapatnam
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Potential Energy Surfaces ◽  
Force Fields ◽  
Pair Potential ◽  
Potential Surfaces ◽  
Empirical Potential ◽  
Functional Forms ◽  
Dynamics Simulations ◽  
Energy Surfaces

When the system of interest becomes too complex to permit the use of ab initio methods to obtain the system potential-energy surfaces (PES), empirical potential surfaces are frequently employed to represent the force fields present in the system under investigation. In most cases, the functional forms present in these potentials are selected on the basis of chemical and physical intuitions. The parameters of the surface are frequently adjusted to fit a very small set of experimental data that comprise bond energies, equilibrium bond distances and angles, fundamental vibrational frequencies, and perhaps measured barrier heights to reactions of interest. Such potentials generally yield only qualitative or semiquantitative descriptions of the system dynamics. Several research groups have significantly improved the accuracy of the values of the experimental properties computed using empirical potential surfaces by fitting the chosen functional form for the potential to the force fields obtained from trajectories using ab initio Car-Parrinello molecular dynamics simulations. The fitting to the force fields is usually done using a least-squares fitting approach. This method has been employed by Izvekov et al. to obtain effective non-polarizable three-site force fields for liquid water. Carré et al. have employed such a procedure to obtain a new pair potential for silica. In their investigation, the vector of potential parameters was fitted using an iterative Levenberg-Marquardt algorithm. Tangney and Scandolo have also developed an interatomic force field for liquid SiO2 in which the parameters were fitted to the forces, stresses, and energies obtained from ab initio calculations. Ercolessi and Adams have used a quasi-Newtonian procedure to fit an empirical potential for aluminum to data obtained from first-principals computations. Empirical potentials can be improved by making the parameters parameterized functions of the coordinates defining the instantaneous positions of the atoms of the system. This approach has been successfully employed by numerous investigators The difficulty with this procedure is that the number of parameters that must be adjusted increases rapidly. Appropriate fitting of these parameters requires a much more extensive database. Finally, the actual fitting process can often be tedious, difficult, and time-consuming.

Potential Energy Surface Calculations of Alanine Dipeptide using BVWN Density Functional Approach and 6-311G Basis Set

2009 ◽  
Vol 1219 ◽  
Author(s):  
Jyoti Singh ◽  
Subhash Chandra Singh ◽  
Narsingh Bahadur Singh
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Basis Set ◽  
Reaction Coordinates ◽  
Conformational Properties ◽  
Energy Surfaces ◽  
Polypeptide Chains ◽  
Alanine Dipeptide

AbstractThis work is devoted to a study of the conformational properties of alanine dipeptide. We have studied potential energy surfaces of alanine dipeptide molecule using density functional theoretical approach with 6-311G basis set. For this purpose potential energies of this molecule are calculated as a function of Ramachandran angles φ and ψ, which are important factors for the characterizations of polypeptide chains. These degrees of freedoms φ and ψ are important for the characterization of protein folding systems. Stable conformations, energy barriers and reaction coordinates of this important dipeptide molecule are calculated. Energy required for the transition of one conformation into other are also discussed.

scholarly journals Benchmark ab initio and dynamical characterization of the stationary points of reactive atom + alkane and SN2 potential energy surfaces

2020 ◽  
Vol 22 (8) ◽  
pp. 4298-4312 ◽  
Author(s):  
Gábor Czakó ◽  
Tibor Győri ◽  
Balázs Olasz ◽  
Dóra Papp ◽  
István Szabó ◽  
...  
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Potential Energy Surfaces ◽  
Stationary Points ◽  
Ion Molecule Reactions ◽  
Energy Surfaces ◽  
Reactive Atom

We review composite ab initio and dynamical methods and their applications to characterize stationary points of atom/ion + molecule reactions.

POTENTIAL ENERGY SURFACES AND MICROWAVE SPECTRA FOR 20Ne–13C16O2, 22Ne–12C16O2 and 22Ne–13C16O2 COMPLEXES

2012 ◽  
Vol 11 (06) ◽  
pp. 1175-1182 ◽  
Author(s):  
RONG CHEN ◽  
HUA ZHU
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Global Minimum ◽  
Energy Levels ◽  
Three Dimensional ◽  
Lanczos Algorithm ◽  
Potential Surfaces ◽  
Microwave Spectra ◽  
Stretching Vibration ◽  
Energy Surfaces

We report averaged potential energy surfaces for isotopic Ne–CO2 complexes (20 Ne –13 C 16 O 2, 22 Ne –12 C 16 O 2 and 22 Ne –13 C 16 O 2). According to the latest ab initio potential of 20 Ne –12 C 16 O 2 (Chen R, Jiao EQ, Zhu H, Xie DQ, J Chem Phys133:104302, 2010) including the Q3 normal mode for the υ3 antisymmetric stretching vibration of the CO2 molecule. We obtain the averaged potentials for 20 Ne –13 C 16 O 2, 22 Ne –12 C 16 O 2 and 22 Ne –13 C 16 O 2 by the integration of the three-dimensional potential over the Q3 coordinate. The averaged potential surfaces are found to have a T-shaped global minimum and two equivalent linear local minima. The radial DVR/angular FBR method and the Lanczos algorithm are applied to calculate the rovibrational energy levels. Comparison with the available observed values showed an overall excellent agreement for all spectroscopic parameters and the microwave spectra.

Vibrationally Averaged Potential Energy Surfaces and Microwave Spectra for Isotopic Ne-CO2 Complexes

2014 ◽  
Vol 670-671 ◽  
pp. 235-239
Author(s):  
Rong Chen ◽  
Xiao Ling Luo
Keyword(s):  
Potential Energy ◽  
Normal Mode ◽  
Potential Energy Surfaces ◽  
Energy Levels ◽  
Chem Phys ◽  
Lanczos Algorithm ◽  
Potential Surfaces ◽  
Microwave Spectra ◽  
Stretching Vibration ◽  
Energy Surfaces

Averaged potential energy surfaces for isotopic Ne–CO2complexes (20Ne–18O13C16O,20Ne–17O12C16O and22Ne–17O12C16O) are presented. According to the latestab initiopotential of20Ne–12C16O2(R. Chen, H. Zhu, D. Q. Xie, J. Chem. Phys, 133, 2010, 104302,) which incorporates its dependence on theQ3normal mode for the antisymmetric stretching vibration of the CO2molecule, we obtain the averaged potentials for20Ne–18O13C16O,20Ne–17O12C16O and22Ne–17O12C16O complexes by integrating the potential energy surface overQ3normal mode. Each averaged potential surfaces are found to have a T-shaped global minimum and two equivalent linear local minima. The radial DVR/angular FBR method and the Lanczos algorithm are applied to calculate the rovibrational energy levels. Comparison with the available experimental values showed an overall excellent agreement for all spectroscopic parameters and the microwave spectra.

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