SINGLET METHYLENE AND HALOCARBENES INSERTIONS INTO POLAR N–H BONDS OF AMINES

2009 ◽  
Vol 08 (06) ◽  
pp. 1143-1153 ◽  
Author(s):  
K. RAMASAMI ◽  
M. RAMALINGAM ◽  
P. VENUVANALINGAM
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Barrier Height ◽  
Energy Surface ◽  
Basis Set ◽  
Proton Shift ◽  
Surface Exploration ◽  
Charge Analysis ◽  
Step Mechanism ◽  
Singlet Methylene

The insertion of singlet 1CH2 , 1CHF , and 1CF2 into polar N–H bonds of RNH2 ( R = –CH3, –C2H5, –C3H7 or –CH(CH3)2 ) has been investigated at HF, MP2, and DFT levels using 6-31g (d, p) basis set. The insertions proceed via a two-step mechanism. The potential energy surface exploration identifies an ylide formation followed by the 1,2-proton shift concertedly giving the secondary amine. The barrier height varies with the type of carbene and amine. HOMO of amines and LUMO of carbenes control the initial interactions and it is confirmed by NBO charge analysis.

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 Accurate global potential energy surface for the ground state of CH2+ by extrapolation to the complete basis set limit

RSC Advances ◽  
2018 ◽  
Vol 8 (25) ◽  
pp. 13635-13642 ◽  
Author(s):  
Lu Guo ◽  
Hongyu Ma ◽  
Lulu Zhang ◽  
Yuzhi Song ◽  
Yongqing Li
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ground State ◽  
Energy Surface ◽  
Correlation Energy ◽  
Basis Set ◽  
Basis Sets ◽  
Complete Basis ◽  
Complete Basis Set ◽  
Complete Basis Set Limit

A full three-dimensional global potential energy surface is reported for the ground state of CH2+ by fitting accurate multireference configuration interaction energies calculated using aug-cc-pVQZ and aug-cc-pV5Z basis sets with extrapolation of the electron correlation energy to the complete basis set limit.

scholarly journals The Interaction between Graphene and Oxygen Atom

Open Physics ◽  
2016 ◽  
Vol 14 (1) ◽  
pp. 690-694 ◽  
Author(s):  
Yifan Hao ◽  
Xuejun Zhao ◽  
Xuedan Song ◽  
Hongjiang Li ◽  
Xiaobing Zhu ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Oxygen Atom ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Density Function ◽  
Energy Surface ◽  
Function Theory ◽  
Dft Method ◽  
Density Function Theory ◽  
Basis Set

AbstractBased on the density function theory (DFT) method, the interaction between the graphene and oxygen atom is simulated by the B3LYP functional with the 6-31G basis set. Due to the symmetry of graphene (C54H18, D6h), a representative patch is put forward to represent the whole graphene to simplify the description. The representative patch on the surface is considered to gain the potential energy surface (PES). By the calculation of the PES, four possible stable isomers of the C54H18-O radical can be obtained. Meanwhile, the structures and energies of the four possible stable isomers, are further investigated thermodynamically, kinetically, and chemically. According to the transition states, the possible reaction mechanism between the graphene and oxygen atom is given.

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>

Sign in / Sign up

Export Citation Format

Share Document