scholarly journals Quantum equation of motion for computing molecular excitation energies on a noisy quantum processor

2020 ◽  
Vol 2 (4) ◽  
Author(s):  
Pauline J. Ollitrault ◽  
Abhinav Kandala ◽  
Chun-Fu Chen ◽  
Panagiotis Kl. Barkoutsos ◽  
Antonio Mezzacapo ◽  
...  
Keyword(s):  
Equation Of Motion ◽  
Excitation Energies ◽  
Quantum Equation ◽  
Quantum Processor ◽  
Molecular Excitation

Tensor Hypercontraction Equation-of-Motion Second-Order Approximate Coupled Cluster: Electronic Excitation Energies in O(N4) Time

2013 ◽  
Vol 117 (42) ◽  
pp. 12972-12978 ◽  
Author(s):  
Edward G. Hohenstein ◽  
Sara I. L. Kokkila ◽  
Robert M. Parrish ◽  
Todd J. Martínez
Keyword(s):  
Electronic Excitation ◽  
Equation Of Motion ◽  
Second Order ◽  
Coupled Cluster ◽  
Excitation Energies

Superconducting and Normal State Properties of the A3C60 Compounds

1992 ◽  
Vol 06 (23n24) ◽  
pp. 3967-3991 ◽  
Author(s):  
Károly Holczer
Keyword(s):  
Normal State ◽  
Local Property ◽  
Alkali Atom ◽  
Density Of State ◽  
Excitation Energies ◽  
Cubic Symmetry ◽  
Normal State Properties ◽  
Molecular Excitation ◽  
Superconducting Parameters ◽  
Expected Density

The A 3 C 60 compounds, where A=alkali atom, form fcc -lattices (cryolite structure) and are highly ionic [ A +]3·[ C 60]3−. The C 60 icosahedra are located in sites of local cubic symmetry thereby preserving the degeneracy of the t 1u orbitals, allowing for the formation of a narrow half filled band of a width comparable to or smaller than the various molecular excitation energies. The T c - s of the dozen or so compounds already synthesized span the range from 2–33 K; the variation of T c with pressure and from material to material suggests that the attraction responsible for the Cooper pair formation is a local property of the C 60 molecules, so that variations of the density-of-state ρ(ε F ) at the Fermi level (i.e. bandwidth) determine T c . The values of the superconducting parameters, λ L and ξ o , determined from critical field and µSR measurements, favor a local pairing picture, but are at best only marginally supportive for the expected density-ofstate variations. The so far available 13 C nuclear relaxation, susceptibility and ESR measurements in the normal state manifest several features that are more related to the complex correlated nature of the C 60 molecules than to the freeelectron band effects of the simple lattice they are arranged in.

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