scholarly journals Unitary transformation from color-spin to isospin-spin coupling schemes for six-quark color singlet states

1989 ◽  
Vol 39 (5) ◽  
pp. 2030-2035 ◽  
Author(s):  
Fl. Stancu
Keyword(s):  
Unitary Transformation ◽  
Spin Coupling ◽  
Color Singlet ◽  
Singlet States

scholarly journals On the Color-Singlet States in Many-Quark Model with the $su(4)$-Algebraic Structure. III

2011 ◽  
Vol 126 (2) ◽  
pp. 313-330
Author(s):  
Yasuhiko Tsue ◽  
Constança Providência ◽  
João da Providência ◽  
Masatoshi Yamamura
Keyword(s):  
Quark Model ◽  
Algebraic Structure ◽  
Color Singlet ◽  
Singlet States

ON THE STRONG VAN DER WAALS FORCES BETWEEN HADRONS DUE TO CONFINING POTENTIALS

1987 ◽  
Vol 02 (01) ◽  
pp. 265-272 ◽  
Author(s):  
A. O. BARUT ◽  
R. RACZKA
Keyword(s):  
Long Range ◽  
Bound States ◽  
Degrees Of Freedom ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Color Singlet ◽  
Singlet States ◽  
Color Scheme

The problem of long range forces between hadrons is re-examined. Without color degrees of freedom the confining potentials lead to unacceptably large van der Waals forces. The color degrees of freedom are investigated in the case of mesons taking into account both of the color singlet states of four constituents. The consistency of the color scheme requires the existence of four-quark bound states as well as two separate mesons and puts still restrictions on the confining potentials.

Color-singlet states in a hadronic quark-cluster basis

1987 ◽  
Vol 2 (4) ◽  
pp. 145-154 ◽  
Author(s):  
P. Gonz�lez ◽  
V. Vento
Keyword(s):  
Color Singlet ◽  
Singlet States

scholarly journals On the Color-Singlet States in Many-Quark Model with the su(4)-Algebraic Structure. I

2011 ◽  
Vol 126 (1) ◽  
pp. 115-134
Author(s):  
Yasuhiko Tsue ◽  
Constança Providência ◽  
João da Providência ◽  
Masatoshi Yamamura
Keyword(s):  
Quark Model ◽  
Algebraic Structure ◽  
Color Singlet ◽  
Singlet States

FRACTIONAL CHARGED COLOR SINGLET STATES AND STRING UNIFICATION

1992 ◽  
Vol 07 (16) ◽  
pp. 1485-1495 ◽  
Author(s):  
DAVID BAILIN ◽  
ALEX LOVE
Keyword(s):  
Gauge Group ◽  
Gauge Coupling ◽  
Low Energy ◽  
Coupling Constants ◽  
Grand Unification ◽  
Color Singlet ◽  
Singlet States ◽  
Gauge Couplings

The question of whether contributions of exotic multiplets of the gauge group to the running of gauge coupling constants from the string scale to low energy can lead to consistency with the precision low energy values of gauge couplings is discussed for theories with SO(6)×SO(4), SU(3)×SU(3)×SU(3) and flipped SU(5)×U(1) grand unification.

Vibrational and thermal averaging of the indirect nuclear spin-spin coupling constants of CH4, SiH4, GeH4 and SnH4

1997 ◽  
Vol 91 (5) ◽  
pp. 897-907 ◽  
Author(s):  
SHEELA KIRPEKAR ◽  
THOMAS ENEVOLDSEN ◽  
JENS ODDERSHEDE ◽  
WILLIAM RAYNES
Keyword(s):  
Nuclear Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

The Interplay of Open-Shell Spin-Coupling and Jahn-Teller Distortion in Benzene Radical Cation Probed by X-ray Spectroscopy

2020 ◽  
Author(s):  
Marta L. Vidal ◽  
Michael Epshtein ◽  
Valeriu Scutelnic ◽  
Zheyue Yang ◽  
Tian Xue ◽  
...  
Keyword(s):  
High Harmonic ◽  
Open Shell ◽  
Spin Coupling ◽  
High Symmetry ◽  
Teller Distortion ◽  
Spectral Window ◽  
X Ray ◽  
Jahn Teller ◽  
X Ray Absorption ◽  
Jahn Teller Distortion

We report a theoretical investigation and elucidation of the x-ray absorption spectra of neutral benzene and of the benzene cation. The generation of the cation by multiphoton ultraviolet (UV) ionization as well as the measurement of<br>the carbon K-edge spectra of both species using a table-top high-harmonic generation (HHG) source are described in the companion experimental paper [M. Epshtein et al., J. Phys.<br>Chem. A., submitted. Available on ChemRxiv]. We show that the 1sC -> pi transition serves as a sensitive signature of the transient cation formation, as it occurs outside of the spectral window of the parent neutral species. Moreover, the presence<br>of the unpaired (spectator) electron in the pi-subshell of the cation and the high symmetry of the system result in significant differences relative to neutral benzene in the spectral features associated with the 1sC ->pi* transitions. High-level calculations using equation-of-motion coupled-cluster theory provide the interpretation of the experimental spectra and insight into the electronic structure of benzene and its cation.<br>The prominent split structure of the 1sC -> pi* band of the cation is attributed to the interplay between the coupling of the core -> pi* excitation with the unpaired electron<br>in the pi-subshell and the Jahn-Teller distortion. The calculations attribute most of<br>the splitting (~1-1.2 eV) to the spin coupling, which is visible already at the Franck-Condon structure, and estimate the additional splitting due to structural relaxation to<br>be around ~0.1-0.2 eV. These results suggest that x-ray absorption with increased resolution might be able to disentangle electronic and structural aspects of the Jahn-Teller<br>effect in benzene cation.<br>

Exchange Spin Coupling from Gaussian Process Regression

2020 ◽  
Author(s):  
Marc Philipp Bahlke ◽  
Natnael Mogos ◽  
Jonny Proppe ◽  
Carmen Herrmann
Keyword(s):  
Machine Learning ◽  
Gaussian Process ◽  
Gaussian Process Regression ◽  
Molecular Magnets ◽  
Molecular Structures ◽  
Spin Coupling ◽  
Structure Property ◽  
Data Set ◽  
Uncertainty Estimates

Heisenberg exchange spin coupling between metal centers is essential for describing and understanding the electronic structure of many molecular catalysts, metalloenzymes, and molecular magnets for potential application in information technology. We explore the machine-learnability of exchange spin coupling, which has not been studied yet. We employ Gaussian process regression since it can potentially deal with small training sets (as likely associated with the rather complex molecular structures required for exploring spin coupling) and since it provides uncertainty estimates (“error bars”) along with predicted values. We compare a range of descriptors and kernels for 257 small dicopper complexes and find that a simple descriptor based on chemical intuition, consisting only of copper-bridge angles and copper-copper distances, clearly outperforms several more sophisticated descriptors when it comes to extrapolating towards larger experimentally relevant complexes. Exchange spin coupling is similarly easy to learn as the polarizability, while learning dipole moments is much harder. The strength of the sophisticated descriptors lies in their ability to linearize structure-property relationships, to the point that a simple linear ridge regression performs just as well as the kernel-based machine-learning model for our small dicopper data set. The superior extrapolation performance of the simple descriptor is unique to exchange spin coupling, reinforcing the crucial role of choosing a suitable descriptor, and highlighting the interesting question of the role of chemical intuition vs. systematic or automated selection of features for machine learning in chemistry and material science.

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