Calculations of models of the σ-electron structure of molecules. III. On the localizability of the ground state σ-molecular orbitals of acetylene, ethylene, and ethane

1968 ◽  
Vol 33 (9) ◽  
pp. 2765-2778 ◽  
Author(s):  
R. Polák
Keyword(s):  
Ground State ◽  
Molecular Orbitals ◽  
Electron Structure ◽  
Structure Of Molecules

STABLE STRUCTURES, ELECTRIC AND MAGNETIC PROPERTIES OF NANOPARTICLES COn(n = 1-6) CLUSTERS: FIRST-PRINCIPLES CALCULATIONS

2013 ◽  
Vol 27 (15) ◽  
pp. 1362007
Author(s):  
JUN LIU ◽  
SHENG-BIAO TAN ◽  
HUI-NING DONG
Keyword(s):  
Magnetic Properties ◽  
Ground State ◽  
First Principles ◽  
Lower Energy ◽  
Magnetic Moments ◽  
Molecular Orbitals ◽  
First Principles Calculations ◽  
Half Metallicity ◽  
Ground State Structures ◽  
Stable Structures

The ground state geometric structures of the nanoparticles or clusters CO n(n = 1-6) were given based on the first-principles calculations. Then the magnetic properties of the clusters CO n(n = 1-6) and ( CO n)-2(n = 1-6) were calculated in system. Results show that their ground state structures are closely related to the numbers of O-ions. These clusters have no magnetic moments and half-metallicity if they are electroneutral. However, they have magnetic moments if they have positive or negative charges. The total magnetic moments of the clusters ( CO n)-2(n = 1-6, but n≠3) are all 2.0000 μB, and all their ions have contributions to the total magnetic moments. The main reason is that the molecular orbitals with lower energy filled with paired electrons and the molecular orbitals with higher energy are occupied by two electrons in parallel.

The direct calculation of the first-order density matrix for atoms

1965 ◽  
Vol 283 (1393) ◽  
pp. 194-202 ◽  
Keyword(s):  
Perturbation Theory ◽  
Density Matrix ◽  
Ground State ◽  
Direct Calculation ◽  
Molecular Orbitals ◽  
Natural Orbitals ◽  
Mean Values ◽  
First Order ◽  
Order Contribution

The theory of isoelectronic sequences of atoms has been developed as a perturbation theory and is extended here to the calculation of the first-order density matrix. It is shown that the calculation of the first-order contribution to this matrix can be reduced to the solution of a number of one-electron equations. These equations have been solved for the helium ground state, the helium 3 S state and the lithium ground state. From the density matrix, mean values of one-electron operators can be derived by integration. A variety of these mean values is quoted and the significance of the stable values discussed. From the density matrix the natural orbitals can be derived and these are found to be identical with the unrestricted molecular orbitals to terms of zero and first order.

Effect of Ligands on the Photoluminescence Performance of Ir(III) Complexes: A Theoretical Exploration

2013 ◽  
Vol 798-799 ◽  
pp. 219-222
Author(s):  
Jian Po Zhang ◽  
Li Jin ◽  
Xing Jin ◽  
Xiu Yun Sun ◽  
Fu Quan Bai
Keyword(s):  
Charge Transfer ◽  
Ground State ◽  
Electronic Structures ◽  
Spectroscopic Properties ◽  
Molecular Orbitals ◽  
Experimental Results ◽  
Frontier Molecular Orbitals ◽  
Bond Lengths ◽  
Td Dft

A series of iridium (III) complexes (C^N)2Ir (Pic) (C^N = Phi (1), Ppi (2), Mpfpi (3), and Cpfpi (4) have been investigated theoretically to explore their electronic structures and spectroscopic properties. The calculate bond lengths of Ir-N and Ir-O in the ground state agree well with the corresponding experimental results. At the TD-DFT and PCM levels, 1-4 give rise to absorptions at 359, 360, 348, and 335 nm and phosphorescent emissions at 454 , 469, 441, and 425 nm, respectively. The transitions of 1-4 are all attributed to {[d (Ir)+π (C^N)][π*(C^N) or π*(Pic)]} charge transfer. It is shown that the emissions are significantly dominated by the metal participating in the frontier molecular orbitals and affected by the C^N ligands.

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).

A Photoelectron Investigation of the Peroxide Bond

1975 ◽  
Vol 53 (22) ◽  
pp. 3439-3447 ◽  
Author(s):  
R. S. Brown
Keyword(s):  
Dihedral Angle ◽  
Ground State ◽  
Vibrational Frequencies ◽  
Molecular Orbitals ◽  
Photoelectron Spectra ◽  
Raman Spectroscopic ◽  
Orbital Interactions ◽  
Highest Occupied Molecular Orbitals ◽  
Peroxide Bond

The photoelectron spectra of several peroxides and their interpretation is presented. The effects of substituents is separated from vicinal orbital interactions using as a guideline the effect of similar substitution on the ether analogues. It is found that by comparison of Raman spectroscopic frequencies of the peroxide ground state, and vibrational frequencies for the ion (via pes), that the HOMO of peroxides is antibonding with respect to the O—O linkage. Additionally, the dependence of the splitting of the two highest occupied molecular orbitals on dihedral angle is verified by the pe spectra of several well-defined cyclic peroxides. Finally, the pe spectrum of tetramethyl-1,2-dioxacyclobutane (tetramethyl dioxetane) is presented indicating that it is not unlike other cyclic peroxides.

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