scholarly journals Torsional Potential Energy Surfaces of Dinitrobenzene Isomers

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Paul M. Smith ◽  
Mario F. Borunda
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Three Dimensional ◽  
Molecular Structures ◽  
Basis Sets ◽  
Valuable Insight ◽  
Complex Molecules ◽  
Torsional Potential ◽  
Energy Surfaces

The torsional potential energy surfaces of 1,2-dinitrobenzene, 1,3-dinitrobenzene, and 1,4-dinitrobenzene were calculated using the B3LYP functional with 6-31G(d) basis sets. Three-dimensional energy surfaces were created, allowing each of the two C-N bonds to rotate through 64 positions. Dinitrobenzene was chosen for the study because each of the three different isomers has widely varying steric hindrances and bond hybridization, which affect the energy of each conformation of the isomers as the nitro functional groups rotate. The accuracy of the method is determined by comparison with previous theoretical and experimental results. The surfaces provide valuable insight into the mechanics of conjugated molecules. The computation of potential energy surfaces has powerful application in modeling molecular structures, making the determination of the lowest energy conformations of complex molecules far more computationally accessible.

scholarly journals Computational Study of Inversion-topomerization Pathways in 1,3-Dimethylcyclohexane and 1,4-Dimethylcyclohexane: Ab Initio Conformational Analysis

2020 ◽  
Author(s):  
Huiting Bian ◽  
Yifan Zhang ◽  
Yongjin Wang ◽  
Jun Zhao ◽  
Xiaohui Ruan ◽  
...  
Keyword(s):  
Potential Energy ◽  
Conformational Analysis ◽  
Potential Energy Surfaces ◽  
Computational Study ◽  
Three Dimensional ◽  
Boltzmann Distribution ◽  
Molecular Structures ◽  
Stationary Points ◽  
Energy Surfaces ◽  
Cis And Trans

This work concerns the typical conformational behaviors for di-substituted cyclohexanes that inherently depend on spatial orientations of side chains in flexible cyclic ring. The 1,3-dimethylcyclohexane and 1,4-dimethylcyclohexane in both cis- and trans-configurations were focused here to unravel their conformational inversion-topomerization mechanisms. Full geometry optimizations were performed at B3LYP/6-311++G(d,p) level of theory to explicitly identify all distinguishable molecular structures, and thus explore potential energy surfaces (PES) of the complete interconversion routes for two stereoisomers of 1,3-dimethylcyclohexane and 1,4-dimethylcyclohexane. Additional quantum calculations were carried out by separately applying MP2/6-311++G(d,p), G4, and CCSD(T)/6-311++G(d,p) methods to further refine all PES’ stationary points. With respect to quantum results, the conformational analysis was conducted to gain insight into the determination, thermodynamic stabilities, and relative energies of distinct molecular geometric structures. On base of highly biased conformational equilibria, the temperature-dependent populations of stable local minima for four studied dimethylcyclohexanes were obtained by utilizing Boltzmann distribution within 300-2500 K. Moreover, two unique interconversion processes for them, including inversion and topomerization, were fully investigated, and their potential energy surfaces were illustrated with the rigorous descriptions in two or three-dimensional schemes for clarify.

THEORETICAL TRANSITION PROBABILITIES FOR THE $\tilde{A}^{2}A_{1} -\tilde{X}^{2}B_{1}$ SYSTEM OF H2O+ AND D2O+ AND RELATED FRANCK–CONDON FACTORS BASED ON GLOBAL POTENTIAL ENERGY SURFACES

2005 ◽  
Vol 04 (01) ◽  
pp. 225-245 ◽  
Author(s):  
IKUO TOKUE ◽  
KATSUYOSHI YAMASAKI ◽  
SATOSHI MINAMINO ◽  
SHINKOH NANBU
Keyword(s):  
Potential Energy ◽  
Photoelectron Spectroscopy ◽  
Potential Energy Surfaces ◽  
Least Squares Method ◽  
Transition Probabilities ◽  
Three Dimensional ◽  
Equilibrium Geometry ◽  
Condon Factors ◽  
Energy Surfaces ◽  
Franck Condon

To elucidate the ionization dynamics, in particular the vibrational distribution, of H 2 O +(Ã) produced by photoionization and the Penning ionization of H 2 O and D 2 O with He *(2 3S) atoms, Franck–Condon factors (FCFs) were given for the [Formula: see text] ionization, and the transition probabilities were presented for the [Formula: see text] emission. The FCFs were obtained by quantum vibrational calculations using the three-dimensional potential energy surfaces (PESs) of [Formula: see text] and [Formula: see text] electronic states. The global PESs were determined by the multi-reference configuration interaction calculations with the Davidson correction and the interpolant moving least squares method combined with the Shepard interpolation. The obtained FCFs exhibit that the [Formula: see text] state primarily populates the vibrational ground state, as its equilibrium geometry is almost equal to that of [Formula: see text], while the bending mode (ν2) is strongly enhanced for the H 2 O +(Ã) state; the maximums in the population of H 2 O + and D 2 O + are approximately v2 = 11–12 and 15–17, respectively. These results are consistent with the distributions observed by photoelectron spectroscopy. Transition probabilities for the [Formula: see text] system of H 2 O + and D 2 O + show that the bending progressions consist primarily of the [Formula: see text] emission, with combination bands from the (1, v′2 = 4–8, 0) level being next most important.

scholarly journals DFT Study on Adsorption of Acetone and Toluene on Silicene

2020 ◽  
Vol 36 (1) ◽  
Author(s):  
Pham Trong Lam ◽  
Ta Thi Luong ◽  
Vo Van On ◽  
An Dinh Van
Keyword(s):  
Charge Transfer ◽  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Adsorption Mechanism ◽  
Simulation Method ◽  
Dft Study ◽  
Gap Opening ◽  
Energy Surfaces ◽  
And Diffusion

In this work, we investigated the adsorption mechanism of acetone and toluene on the surface of silicene by the quantum simulation method. The images of the potential energy surfaces for different positions of the adsorbate on the silicene surface were explored by Computational DFT-based Nanoscope tool for determination of the most stable configurations and diffusion possibilities. The charge transfer in order of 0.2 – 0.3 electrons and the tunneling gap opening of 18 – 23 meV due to acetone and toluene, respectively, suggest that silicene is considerably sensitive with these VOCs and can be used as the material in the fabrication of reusable VOC sensors.

scholarly journals Three-dimensional potential energy surfaces of ArNO (X̃ 2Π)

2020 ◽  
Vol 152 (11) ◽  
pp. 114302
Author(s):  
Alexander Teplukhin ◽  
Brian K. Kendrick
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Three Dimensional ◽  
Energy Surfaces
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