scholarly journals Frustrated spin-12J1−J2Heisenberg ferromagnet on the square lattice studied via exact diagonalization and coupled-cluster method

2010 ◽  
Vol 81 (17) ◽  
Author(s):  
J. Richter ◽  
R. Darradi ◽  
J. Schulenburg ◽  
D. J. J. Farnell ◽  
H. Rosner
Keyword(s):  
Exact Diagonalization ◽  
Square Lattice ◽  
Cluster Method ◽  
Coupled Cluster ◽  
Coupled Cluster Method ◽  
Frustrated Spin

scholarly journals FRUSTRATED QUANTUM ANTIFERROMAGNETS: APPLICATION OF HIGH-ORDER COUPLED CLUSTER METHOD

2007 ◽  
Vol 21 (13n14) ◽  
pp. 2273-2288 ◽  
Author(s):  
J. RICHTER ◽  
R. DARRADI ◽  
R. ZINKE ◽  
R. F. BISHOP
Keyword(s):  
Ground State ◽  
Quantum Phase Transitions ◽  
Classical Model ◽  
Interlayer Coupling ◽  
Square Lattice ◽  
Cluster Method ◽  
Coupled Cluster ◽  
Two Dimensional ◽  
Coupled Cluster Method ◽  
State Present

We report on recent results for strongly frustrated quantum J1 - J2 antiferromagnets in dimensionality d = 1, 2, 3 obtained by the coupled cluster method (CCM). We demonstrate that the CCM in high orders of approximation allows us to investigate quantum phase transitions driven by frustration and to discuss novel quantum ground states. In detail we consider the ground-state properties of (i) the Heisenberg spin-1/2 antiferromagnet on the cubic lattice in d = 1, 2, 3, and use the results for the energy, the sublattice magnetization and the spin stiffness as a benchmark test for the precision of the method; (ii) coupled frustrated spin chains (the quasi-one-dimensional J1 - J2 model) and discuss the influence of the quantum fluctuations and the interchain coupling on the incommensurate spiral state present in the classical model; (iii) the Shastry-Sutherland antiferromagnet on the square lattice; and (iv) a stacked frustrated square-lattice Heisenberg antiferromagnet (the quasi-two-dimensional J1 - J2 model), and discuss the influence of the interlayer coupling on the quantum paramagnetic ground-state phase that is present for the strictly two-dimensional model.

The relativistic coupled-cluster method: transition energies of bismuth and eka-bismuth

1998 ◽  
Vol 94 (1) ◽  
pp. 181-187 ◽  
Author(s):  
EPHRAIM ELIAV ◽  
UZI KALDOR ◽  
YASUYUKI ISHIKAWA
Keyword(s):  
Cluster Method ◽  
Coupled Cluster ◽  
Coupled Cluster Method ◽  
Transition Energies

A Multi-Layer Approach to the Equation of Motion Coupled-Cluster Method for the Electron Affinity

2020 ◽  
Author(s):  
Soumi Haldar ◽  
Achintya Kumar Dutta
Keyword(s):  
Electron Affinity ◽  
Electron Attachment ◽  
Equation Of Motion ◽  
Cluster Method ◽  
Coupled Cluster ◽  
Coupled Cluster Method ◽  
Large Molecules ◽  
Layer Method ◽  
Speed Up ◽  
Attachment Process

We have presented a multi-layer implementation of the equation of motion coupled-cluster method for the electron affinity, based on local and pair natural orbitals. The method gives consistent accuracy for both localized and delocalized anionic states. It results in many fold speedup in computational timing as compared to the canonical and DLPNO based implementation of the EA-EOM-CCSD method. We have also developed an explicit fragment-based approach which can lead to even higher speed-up with little loss in accuracy. The multi-layer method can be used to treat the environmental effect of both bonded and non-bonded nature on the electron attachment process in large molecules.<br>

Coupled-cluster method in Fock space. II. Brueckner-Hartree-Fock method

1985 ◽  
Vol 32 (2) ◽  
pp. 743-747 ◽  
Author(s):  
Leszek Z. Stolarczyk ◽  
Hendrik J. Monkhorst
Keyword(s):  
Fock Space ◽  
Cluster Method ◽  
Coupled Cluster ◽  
Coupled Cluster Method ◽  
Hartree Fock

Intermediate Hamiltonian Hilbert space coupled cluster method: Theory and pilot application

2009 ◽  
Vol 109 (13) ◽  
pp. 2909-2915 ◽  
Author(s):  
Ephraim Eliav ◽  
Anastasia Borschevsky ◽  
K. R. Shamasundar ◽  
Sourav Pal ◽  
Uzi Kaldor
Keyword(s):  
Hilbert Space ◽  
Cluster Method ◽  
Coupled Cluster ◽  
Coupled Cluster Method
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