AB INITIO POTENTIAL ENERGY SURFACE AND PREDICTED ROVIBRATIONAL SPECTRA FOR THE Kr–N2O COMPLEX

2008 ◽  
Vol 07 (05) ◽  
pp. 1093-1102 ◽  
Author(s):  
RONG CHEN ◽  
HUA ZHU
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Energy Levels ◽  
Basis Set ◽  
Spectroscopic Constants ◽  
Basis Set Superposition Error ◽  
Rovibrational Spectra ◽  
Bond Functions ◽  
Representation Method

The potential energy surface for the Kr – N 2 O complex is calculated using the coupled-cluster singles and doubles with noniterative inclusion of connected triples [CCSD(T)] with a large basis set including midpoint bond functions. The interaction energies are obtained by the supermolecular approach with the full counterpoise correction for the basis set superposition error. The CCSD(T) potential is found to have two minima corresponding to the T-shaped and linear Kr – ONN structures. The geometry for the T-shaped configuration is very close to the experimental results. The two-dimensional discrete variable representation method is applied to calculate the rovibrational energy levels with N 2 O at its ground and ν3 excited states. The calculated transition frequencies and spectroscopic constants are in good agreement with the observed values.

scholarly journals Intermolecular Lennard-Jones (22-11)Potential Energy Surface in Dimer of N8 Cubane Cluster

2017 ◽  
Vol 59 (2) ◽  
Author(s):  
Jamshid Najafpour
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Density Functional ◽  
Energy Surface ◽  
Separation Distance ◽  
Basis Set ◽  
Intermolecular Potential ◽  
Basis Set Superposition Error ◽  
Lennard Jones

<p>We have calculated the intermolecular potential energy surface (IPES) of the dimer of cubic N8 cluster using <em>ab initio </em>and the density functional theory (DFT) calculations. The <em>ab initio </em>(HF/3- 21G(d)) and DFT (B3LYP/6-31G(d) and aug-cc-pVDZ) calculations were performed for two relative orientations of N8-N8 system as a function of separation distance between the centers of cubic N8 clusters. In this research, the IPES, <em>U</em>(<em>r</em>), of the N8-N8 system is studied, where the edge of N8 approaches to face or edge of the other considered N8. Then, the Lennard-Jones (12-6) and (22-11) adjustable parameters are fitted to the computed interaction energies for edge-face and edge-edge orientations. In this research for the first time, the IPESs proportionated to the Lennard-Jones (22-11) potential are derived that are compatible with the computed IPES curves. Assuming a set of Lennard-Jones parameters, the second virial coefficients are obtained for the N8-N8 complex at a temperature range of 298 to 1000 K. Both the corrected and uncorrected basis set superposition error (BSSE) results are presented confirming the significance of including BSSE corrections.</p>

Rotational de-excitations of C3H+ (1Σ+) by collision with He: new ab initio potential energy surface and scattering calculations

2020 ◽  
Vol 494 (4) ◽  
pp. 5675-5681 ◽  
Author(s):  
Sanchit Chhabra ◽  
T J Dhilip Kumar
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Cross Sections ◽  
Energy Surface ◽  
Molecular Ions ◽  
Basis Set ◽  
Rate Coefficients ◽  
Close Coupling ◽  
Collisional Rate Coefficients

ABSTRACT Molecular ions play an important role in the astrochemistry of interstellar and circumstellar media. C3H+ has been identified in the interstellar medium recently. A new potential energy surface of the C3H+–He van der Waals complex is computed using the ab initio explicitly correlated coupled cluster with the single, double and perturbative triple excitation [CCSD(T)-F12] method and the augmented correlation consistent polarized valence triple zeta (aug-cc-pVTZ) basis set. The potential presents a well of 174.6 cm−1 in linear geometry towards the H end. Calculations of pure rotational excitation cross-sections of C3H+ by He are carried out using the exact quantum mechanical close-coupling approach. Cross-sections for transitions among the rotational levels of C3H+ are computed for energies up to 600 cm−1. The cross-sections are used to obtain the collisional rate coefficients for temperatures T ≤ 100 K. Along with laboratory experiments, the results obtained in this work may be very useful for astrophysical applications to understand hydrocarbon chemistry.

THE H2NO POTENTIAL ENERGY SURFACE EXPLORED WITH HIGH LEVEL AB INITIO AND DENSITY FUNCTIONAL THEORY METHODS

2007 ◽  
Vol 06 (03) ◽  
pp. 549-562
Author(s):  
ABRAHAM F. JALBOUT
Keyword(s):  
Density Functional Theory ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Density Functional ◽  
Energy Surface ◽  
Hybrid Methods ◽  
Transition States ◽  
Basis Set ◽  
Functional Theory ◽  
High Level

The transition states for the H 2 NO decomposition and rearrangements mechanisms have been explored by the CBS-Q method or by density functional theory. Six transition states were located on the potential energy surface, which were explored with the Quadratic Complete Basis Set (CBS-Q) and Becke's one-parameter density functional hybrid methods. Interesting deviations between the CBS-Q results and the B1LYP density functional theory lead us to believe that further study into this system is necessary. In the efforts to further assess the stabilities of the transition states, bond order calculations were performed to measure the strength of the bonds in the transition state.

scholarly journals Anab initiobased full-dimensional potential energy surface for OH + O2⇄ HO3and low-lying vibrational levels of HO3

2019 ◽  
Vol 21 (25) ◽  
pp. 13766-13775 ◽  
Author(s):  
Xixi Hu ◽  
Junxiang Zuo ◽  
Changjian Xie ◽  
Richard Dawes ◽  
Hua Guo ◽  
...  
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Quantum Dynamics ◽  
Energy Surface ◽  
Vibrational Energy ◽  
Energy Levels ◽  
Vibrational Levels ◽  
Vibrational Energy Levels

A full-dimensional potential energy surface for HO3, including the HO + O2dissociation asymptote, is developed and rigorous quantum dynamics calculations based on this PES have been carried out to compute the vibrational energy levels of HO3.

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