Journal ArticleDOI
A spin-adapted linear response theory in a coupled-cluster framework for direct calculation of spin-allowed and spin-forbidden transition energies
Somnath Ghosh,Debashis Mukherjee,Subir Bhattacharyya +2 more
- Vol. 72, Iss: 1, pp 161-176
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In this paper, a spin-adapted linear response theory in a coupled-cluster framework was proposed to calculate the spin-allowed and spin-forbidden transition energies from a single methodology.Abstract:
In this paper, we have spin-adapted our recently formulated linear response theory in a coupled-cluster framework. This allows us to calculate directly both the spin-allowed and the spin-forbidden transition energies from a single methodology. We have introduced rank-zero and rank-one spin operators to construct excitation operators for singlet-singlet and singlet-triplet transitions respectively and utilised the graphical methods of spin algebra to integrate the spin variables. It has been shown how a suitable parameterisation of the reduced Hugenholtz matrix elements of the excitation operator in terms of Goldstone matrix elements makes the resulting system of equations simple, compact and suitable for computer implementation. A pilot calculation has been performed to test the applicability of the theory.read more
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Journal ArticleDOI
Ionization potentials of beryllium-like ions from the relativistic coupled-cluster-based linear response theory
Rajat K. Chaudhuri,Prafulla K. Panda,Holger Merlitz,Bhanu Pratap Das,Uttam Sinha Mahapatra,Debashis Mukherjee +5 more
TL;DR: In this paper, the principal and the shake-up ionization potentials (IP) of highly stripped atoms were computed using the relativistic and non-relativistic CCLRT calculations.
Journal ArticleDOI
Application of relativistic coupled cluster linear response theory to helium-like ions embedded in plasma environment
Madhulita Das,Rajat K. Chaudhuri,Sudip Chattopadhyay,Uttam Sinha Mahapatra,Purnendu Mukherjee,Purnendu Mukherjee +5 more
TL;DR: In this paper, the state-of-the-art coupled cluster (CC)-based linear response theory (LRT) with the four-component relativistic spinors was used to estimate the effect of plasma on the ions within the relatvistic and non-relativistic framework, and the transition energies computed at the CCLRT level using the Debye model agree well with experiment and with other available theoretical data.
Journal ArticleDOI
A spin-adapted coupled-cluster based linear response theory for double ionization potentials
TL;DR: In this paper, a spin-adapted formulation of the coupled-cluster based linear response theory (CC-LRT) was developed for computing double-ionization potentials (DIPs), which may be experimentally observed by Auger spectroscopy.
Journal ArticleDOI
Ab initio description of the ground and excited states of cyanogen isomers
TL;DR: In this article, the ground and low lying excited electronic states of several linear and cyclic isomers of cyanogen were characterized for the first time, including the excitation energies for selected singlet and triplet Σ states of NCCN, isocyanogen (CNCN), di-isocynogen (CNNC), diaza-dicarbon (NNCC), and corresponding states of three cyclic cyanogen isomers.
Journal ArticleDOI
Molecular applications of coupled-cluster-based linear response theory: Inner and outer valence ionization potentials of nitrogen and water
TL;DR: In this article, the authors report the first ab initio molecular applications of linear response theory in the coupled-cluster framework for calculating inner and outer valence ionization potentials (IPs).
References
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On the Correlation Problem in Atomic and Molecular Systems. Calculation of Wavefunction Components in Ursell-Type Expansion Using Quantum-Field Theoretical Methods
TL;DR: In this article, a method for the calculation of the matrix elements of the logarithm of an operator which gives the exact wavefunction when operating on the wavefunction in the one-electron approximation is proposed.
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A response-function approach to the direct calculation of the transition-energy in a multiple-cluster expansion formalism
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Correlation problem in open-shell atoms and molecules
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