Effectively Unpaired Electrons for Singlet States: From Diatomics to Graphene Nanoclusters

2016 ◽  
pp. 151-206 ◽  
Author(s):  
Anatoliy V. Luzanov
Keyword(s):  
Singlet States ◽  
Unpaired Electrons

Explaining the magnetism of gold

2017 ◽  
Author(s):  
Robson de Farias
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Formation Enthalpy ◽  
Gold Atom ◽  
Orbital Energy ◽  
Knudsen Effusion ◽  
Energy Diagram ◽  
Unpaired Electrons ◽  
The Difference ◽  
Good Agreement

<p>In the present work, a computational study is performed in order to clarify the possible magnetic nature of gold. For such purpose, gas phase Au<sub>2</sub> (zero charge) is modelled, in order to calculate its gas phase formation enthalpy. The calculated values were compared with the experimental value obtained by means of Knudsen effusion mass spectrometric studies [5]. Based on the obtained formation enthalpy values for Au<sub>2</sub>, the compound with two unpaired electrons is the most probable one. The calculated ionization energy of modelled Au<sub>2</sub> with two unpaired electrons is 8.94 eV and with zero unpaired electrons, 11.42 eV. The difference (11.42-8.94 = 2.48 eV = 239.29 kJmol<sup>-1</sup>), is in very good agreement with the experimental value of 226.2 ± 0.5 kJmol<sup>-1</sup> to the Au-Au bond<sup>7</sup>. So, as expected, in the specie with none unpaired electrons, the two 6s<sup>1</sup> (one of each gold atom) are paired, forming a chemical bond with bond order 1. On the other hand, in Au<sub>2</sub> with two unpaired electrons, the s-d hybridization prevails, because the relativistic contributions. A molecular orbital energy diagram for gas phase Au<sub>2</sub> is proposed, explaining its paramagnetism (and, by extension, the paramagnetism of gold clusters and nanoparticles).</p>

Quasiparticle Excitations in Polyenes and Polyacetylene

1987 ◽  
Vol 109 ◽  
Author(s):  
Paul Tavan ◽  
Klaus Schulten
Keyword(s):  
Dispersion Relations ◽  
Excited Singlet ◽  
Quasi Particle ◽  
Double Excitation ◽  
Singlet States ◽  
Excited Singlet States ◽  
Electron Excitations ◽  
Quasiparticle Excitations

ABSTRACTWe apply the Pariser-Parr-Pople Hamiltonian to study many-electron excitations in polyenes and polyacetylene. The excited singlet states of polyenes, calculated by a multireference double excitation expansion, are classified as quasi-particle excitations, namely as triplet-triplet magnons and particle-hole excitons. From finite polyene spectra we derive approximate dispersion relations for these quasi-particles in the infinite polyene, i.e. polyacetylene.

A decomposition of the number of effectively unpaired electrons and its physical meaning

2009 ◽  
Vol 476 (1-3) ◽  
pp. 101-103 ◽  
Author(s):  
Luis Lain ◽  
Alicia Torre ◽  
Diego R. Alcoba ◽  
Roberto C. Bochicchio
Keyword(s):  
Physical Meaning ◽  
Unpaired Electrons
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