The negative ion BN−and its role in determining the ground state of BN via photodetachment. An MRDCI ab initio study

1993 ◽  
Vol 71 (10) ◽  
pp. 1581-1594 ◽  
Author(s):  
Robert C. Mawhinney ◽  
Pablo J. Bruna ◽  
Friedrich Grein
Keyword(s):  
Excited States ◽  
Ground State ◽  
Experimental Studies ◽  
Electron Attachment ◽  
Radiative Properties ◽  
Basis Set ◽  
Negative Ion ◽  
Resonant States ◽  
Gaussian Basis Set ◽  
Ci Calculations

Extensive multireference CI calculations using a contracted 6s5p3d1f Gaussian basis set on the B and N atoms indicate that the X2∑+, A2Π, and B2∑+ states of BN− are bound with respect to the electron attachment BN + e−. The 14∑+, 14Δ, 14∑−, and 14Π states of BN− are resonant states, all autodetaching into neutral BN. The electron affinity X3Π → X2∑+ is predicted to be 2.84 eV (with a best estimate of 3.10 eV). Other features studied for BN− include the infrared spectrum of the X2∑+ ground state as well as the electronic radiative properties involving the excited states A2Π and B2∑+. The present study supports a X3Π ground state for BN, with a1∑+ lying about 0.03 eV higher. As an alternative to optical spectroscopy on BN, experimental studies of the photodetachment spectrum of BN− are proposed in order to find the ordering and energetic separation of the lowest 3Π and 1∑+ states of BN.

Polarization Gaussian p Functions for the Beryllium Atom: Ab initio Calculations on BeH2 and BeH+

1975 ◽  
Vol 53 (22) ◽  
pp. 2512-2516 ◽  
Author(s):  
P. G. Mezey ◽  
I. G. Csizmadia ◽  
O. P. Strausz
Keyword(s):  
Excited State ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Ground State ◽  
Optimization Procedure ◽  
Energy Functional ◽  
Basis Set ◽  
Negative Ion ◽  
Gaussian Basis Set ◽  
Orbital Exponents

A set of Gaussian p orbital exponents was obtained by optimizing a (9s5p) Gaussian basis set for an excited state of the beryllium atom and the ground state of the beryllium negative ion. In the optimization procedure the method of conjugate gradients was applied for the energy functional. The optimum (9s5p) basis set was tested on the BeH2 and BeH+ structures.

Dissociative Electron Attachment Processes in SO2 and NO2

1971 ◽  
Vol 49 (9) ◽  
pp. 1571-1574 ◽  
Author(s):  
D. A. Rallis ◽  
J. M. Goodings
Keyword(s):  
Kinetic Energy ◽  
Ground State ◽  
Electronic Excitation ◽  
Electron Attachment ◽  
Negative Ion ◽  
Dissociation Limit ◽  
Dissociative Electron Attachment ◽  
Zero Kinetic Energy ◽  
Trapped Electron ◽  
Second Peak

A trapped electron apparatus has been used to identify the processes involved in negative ion formation for the triatomic oxides SO2 and NO2. Two O− peaks are observed in SO2 with onset values at 4.2 ± 0.15 and 6.3 ± 0.2 eV, and peak values at 5.0 ± 0.15 and 7.4 ± 0.15 eV, respectively. From kinetic energy analysis of the O− ions, both peaks are found to have the same dissociation limit involving SO in its ground state. For NO2, two dissociative electron attachment peaks are observed with onset values at 1.6 ± 0.2 and 7.3 ± 0.3 eV, and peak values at 3.0 ± 0.2 and 8.1 ± 0.2 eV, respectively. The first broad peak is explained by overlapping contributions from two processes having the same dissociation limit involving ground state NO; they differ only in the amount of kinetic energy possessed by the fragments. The second peak appears to involve electronic excitation of the neutral fragment NO* with zero kinetic energy at onset.

The ground state and low-lying excited states of CCCN radical and its ions: a CASSCF/CASPT2 study

2016 ◽  
Vol 94 (9) ◽  
pp. 803-807
Author(s):  
Angyang Yu
Keyword(s):  
Excited States ◽  
Ground State ◽  
Linear Structure ◽  
Electronic Configuration ◽  
Geometric Optimization ◽  
Oscillator Strengths ◽  
Basis Set ◽  
Excitation Energies ◽  
Complete Active Space ◽  
Vertical Excitation

The ground state and low-lying excited states of the CCCN radical and its ions have been investigated systematically using the complete active space self-consistent field (CASSCF) and multi-configuration second-order perturbation theory (CASPT2) methods in conjunction with the ANO-RCC-TZP basis set. The calculated results show that the state 12Σ+ has the lowest CASPT2 energy among the electronic states. By means of the geometric optimization of this radical, it could be found that the molecule exhibits linear structure, with the bond lengths R1 = 1.214 Å, R2 = 1.363 Å, R3 = 1.162 Å, which are very close to the experimental values. The calculated vertical excitation energies and the corresponding oscillator strengths show that there are three relatively strong peaks at energies 0.63, 4.04, and 5.49 eV, which correspond to the transitions 12Σ+ → 12Π, 12Σ+ → 22Π, and 12Σ+ → 22Σ+, respectively. Additionally, the electronic configuration and the harmonic vibration frequencies of each state are also investigated.

scholarly journals Ab Initio Analysis of Exchange Interactions in [V2O(BIPY)4CL2]2+ Complex

2008 ◽  
Vol 3 (1) ◽  
pp. 112-117
Author(s):  
Ivan Ogurtsov ◽  
Andrei Tihonovschi
Keyword(s):  
Ab Initio ◽  
Excited States ◽  
Ground State ◽  
Exchange Interactions ◽  
Boltzmann Distribution ◽  
Molecular Orbitals ◽  
Vanadium Complex ◽  
Ferromagnetic Interaction ◽  
Ci Calculations ◽  
D Orbitals

In this work an ab initio analysis of the binuclear vanadium complex [V2O(bipy)4Cl2]2+ electronic structure is performed. The ground state was calculated to be a quintet, which means a ferromagnetic interaction between centers. The orbitals participating in exchange interaction according to ROHF+CI calculations are two molecular orbitals consisting of vanadium d-orbitals and two molecular orbitals with main contributions from p-orbitals of bipyridine ligands perpendicular to V-V axis, vanadium d- and p-orbitals and μ-oxygen p-orbital. Calculated energy values of the multielectronic states are placed in accordance with Lande rule. The value of magnetic moment at 293K calculated for the complex in vacuum taking into consideration the Boltzmann distribution and the energies of the excited states is 3.95BM which is in accordance with experimental value of 3.99BM (for complex in acetone).

SEMIEMPIRICAL SCF CALCULATIONS ON AZULENE AND ITS SINGLY CHARGED IONS

1965 ◽  
Vol 43 (11) ◽  
pp. 3026-3038 ◽  
Author(s):  
J. E. Bloor
Keyword(s):  
Dipole Moment ◽  
Excited States ◽  
Ground State ◽  
Basis Set ◽  
Bond Orders ◽  
Electron Charge Density ◽  
Charge Densities ◽  
Bond Lengths ◽  
Set Agreement ◽  
Singly Charged

SCF MOs for azulene have been obtained by the semiempirical Pariser, Parr, Pople procedure using the Nishimoto–Mataga method of calculating repulsion integrals and the assumption that nearest neighbor resonance integrals are independent of interatomic distance. Excited states calculated from these MOs by a CI calculation are in very good agreement with experiment. Ground state charge densities, bond orders, and the dipole moment are similar to other SCFMO calculations and reveal no disadvantage in adopting a constant resonance integral for all bonds. It is shown that estimates of the π-electron charge density by n.m.r. methods are not compatible with direct dipole moment measurements and it is suggested that the interpretation of the n.m.r. measurements suffers from inaccuracies in estimating ring currents. Doubt is also thrown on the use of simple relationships between calculated π-bond orders and bond lengths obtained by X-ray crystallographic measurements on the solid state, particularly since all the bond lengths in azulene are predicted to be longer than in benzene whereas experiment shows some to be shorter. Calculations on spin densities and charge densities of the singly charged azulene anion and cation have been performed by a restricted Hartree–Fock perturbation method in which the matrix elements for the interaction between singly excited states and the ground state are calculated using the closed shell SCFMOs of azulene as the basis set. Agreement with experiment for the anion is fairly good. For the cation our results are in severe disagreement with recent VB calculations, but there are no experimental results available to decide between the two methods.

Selection of a Gaussian basis set for calculating the Bethe logarithm for the ground state of the hydrogen atom

2013 ◽  
Vol 111 (9-11) ◽  
pp. 1063-1068 ◽  
Author(s):  
Monika Stanke ◽  
Ludwik Adamowicz ◽  
Dariusz Kedziera
Keyword(s):  
Hydrogen Atom ◽  
Ground State ◽  
Basis Set ◽  
Gaussian Basis Set ◽  
Selection Of

Ab Initio-Rechnungen zum F2-Molekül/ Different ab-initio calculations for the ground-state and some excited states of the F2-molecule

1973 ◽  
Vol 28 (5) ◽  
pp. 704-708 ◽  
Author(s):  
E. Kasseckert
Keyword(s):  
Ab Initio ◽  
Excited States ◽  
Ground State ◽  
Good Description ◽  
Basis Functions ◽  
Slater Type Orbitals ◽  
Slater Type ◽  
Ci Calculations ◽  
Potential Curves ◽  
Higher Excited States

For the ground-state and the lower lying excited states of the fluorine-molecule VB -CI calculations with Slater-type orbitals and SCF -CI calculations with contracted Gauß-Lobe functions have been carried out. The SCF -CI method yields a fairly good description of the ground-state. But it is rather difficult to decide whether the SCF -CI calculations of the excited states are accurate or not. The discussion of the potential-curves of some higher excited states leads to the conjecture that the experimentally observed orange band-systems may belong to two transitions1Σg-→ 1Πu and 1Σu+ → 1Πg.But this should be checked in further calculations which must include higher orbitals as basis functions.

Sign in / Sign up

Export Citation Format

Share Document