Orbital Exponent Optimization in Elementary VB Calculations of the Chemical Bond in the Ground State of Simple Molecular Systems

2008 ◽  
Vol 85 (12) ◽  
pp. 1686 ◽  
Author(s):  
Valerio Magnasco
Keyword(s):  
Chemical Bond ◽  
Ground State ◽  
Orbital Exponent ◽  
Molecular Systems

scholarly journals Optical spin-state polarization in a binuclear europium complex towards molecule-based coherent light-spin interfaces

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kuppusamy Senthil Kumar ◽  
Diana Serrano ◽  
Aline M. Nonat ◽  
Benoît Heinrich ◽  
Lydia Karmazin ◽  
...  
Keyword(s):  
Ground State ◽  
Quantum Information Processing ◽  
Optical Transition ◽  
Molecular Engineering ◽  
Coherent Light ◽  
Nuclear Spins ◽  
Rare Earth Ion ◽  
Molecular Systems ◽  
Homogeneous Linewidth ◽  
State Spin

AbstractThe success of the emerging field of solid-state optical quantum information processing (QIP) critically depends on the access to resonant optical materials. Rare-earth ion (REI)-based molecular systems, whose quantum properties could be tuned taking advantage of molecular engineering strategies, are one of the systems actively pursued for the implementation of QIP schemes. Herein, we demonstrate the efficient polarization of ground-state nuclear spins—a fundamental requirement for all-optical spin initialization and addressing—in a binuclear Eu(III) complex, featuring inhomogeneously broadened 5D0 → 7F0 optical transition. At 1.4 K, long-lived spectral holes have been burnt in the transition: homogeneous linewidth (Γh) = 22 ± 1 MHz, which translates as optical coherence lifetime (T2opt) = 14.5 ± 0.7 ns, and ground-state spin population lifetime (T1spin) = 1.6 ± 0.4 s have been obtained. The results presented in this study could be a progressive step towards the realization of molecule-based coherent light-spin QIP interfaces.

scholarly journals A Class of Non-Kekulé Molecules with Low Excitation Energies

2007 ◽  
Vol 62 (11) ◽  
pp. 1433-1436
Author(s):  
Fritz Dietz ◽  
Nedko Drebov ◽  
Nikolai Tyutyulkov
Keyword(s):  
Molecular Orbital ◽  
Ground State ◽  
Excitation Energies ◽  
Triplet Ground State ◽  
Molecular Systems ◽  
Structural Principle

A class of non-Kekulé molecular systems with a new structural principle and low excitation energies or with a triplet ground state was investigated theoretically. The systems consist of a non-Kekulé monoradical, possessing a non-bonding molecular orbital linked in a specific way to another monoradical.

Application of multireference linearized coupled-cluster theory to atomic and molecular systems

2018 ◽  
Vol 17 (02) ◽  
pp. 1850016 ◽  
Author(s):  
Jiang Yi ◽  
Feiwu Chen
Keyword(s):  
Ground State ◽  
Basis Sets ◽  
Coupled Cluster ◽  
Vibration Frequencies ◽  
Electron Affinities ◽  
Proton Affinities ◽  
Coupled Cluster Theory ◽  
Molecular Systems ◽  
Ground State Energies ◽  
Second Order Perturbation Theory

Applications of the multireference linearized coupled-cluster single-doubles (MRLCCSD) to atomic and molecular systems have been carried out. MRLCCSD is exploited to calculate the ground-state energies of HF, H2O, NH3, CH4, N2, BF, and C2with basis sets, cc-pVDZ, cc-pVTZ and cc-pVQZ. The equilibrium bond lengths and vibration frequencies of HF, HCl, Li2, LiH, LiF, LiBr, BH, and AlF are computed with MRLCCSD and compared with the experimental data. The electron affinities of F and CH as well as the proton affinities of H2O and NH3are also calculated with MRLCCSD. These results are compared with the results produced with second-order perturbation theory, linearized coupled-cluster doubles (LCCD), coupled-cluster doubles (CCD), coupled-cluster singles and doubles (CCSD), CCSD with perturbative triples correction (CCSD(T)). It is shown that all results obtained with MRLCCSD are reliable and accurate.

scholarly journals Chemical bond and entanglement of electrons in the hydrogen molecule

2014 ◽  
Vol 12 (05) ◽  
pp. 1450028
Author(s):  
Nikos Iliopoulos ◽  
Andreas F. Terzis
Keyword(s):  
Linear Combination ◽  
Chemical Bond ◽  
Configuration Interaction ◽  
Ground State ◽  
Hydrogen Molecule ◽  
Molecular System ◽  
Quantum Correlations ◽  
Atomic Orbitals ◽  
Analytic Expression ◽  
Electronic Wavefunction

We theoretically investigate the quantum correlations (in terms of concurrence of indistinguishable electrons) in a prototype molecular system (hydrogen molecule). With the assistance of the standard approximations of the linear combination of atomic orbitals and the configuration interaction methods we describe the electronic wavefunction of the ground state of the H 2 molecule. Moreover, we managed to find a rather simple analytic expression for the concurrence (the most used measure of quantum entanglement) of the two electrons when the molecule is in its lowest energy. We have found that concurrence does not really show any relation to the construction of the chemical bond.

scholarly journals Accurate Calculation of the Density of States near the Ground-State Energy of the Peptides Met-Enkephalin and (Alanine)5 with the Wang-Landau Method: Lessons Learned

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Priya Singh ◽  
Pradipta Bandyopadhyay
Keyword(s):  
Density Of States ◽  
Ground State Energy ◽  
Ground State ◽  
Energy Region ◽  
State Energy ◽  
High Energy ◽  
Lessons Learned ◽  
Energy Space ◽  
Current Case ◽  
Molecular Systems

The Wang-Landau method estimates the relative density of states (DOS) by performing random walk in energy space. However, estimation of the DOS near the ground state minimum is highly challenging because of the dearth of states in the low-energy region compared to that at the high-energy region. Ideally the derivative of the logarithm of the DOS with respect to energy, which is proportional to the inverse of temperature, should become steeper with decrease in energy. However, in actual estimation of the DOS for molecular systems, it is nontrivial to achieve this. In the current work, the accuracy of the Wang-Landau method in estimating the DOS near the ground state minimum is investigated for two peptides, Met-enkephalin and (Alanine)5. It has been found that the steepness of the DOS can be achieved if the correct ground state energy is found, the bin used to discretize the energy space is extremely small (0.1 kcal/mol was used in the current case) and the energy range used to estimate the DOS is small. The findings of this work can help in devising new protocols for calculating the DOS with high accuracy near the ground state minimum for molecular systems.

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