scholarly journals Chemical insights into the electronic structure of Fe(II) porphyrin using FCIQMC, DMRG, and generalized active spaces

2020 ◽  
Author(s):  
Oskar Weser ◽  
Leon Freitag ◽  
Kai Guther ◽  
Ali Alavi ◽  
Giovanni Li Manni
Keyword(s):  
Electron Correlation ◽  
Quantitative Measure ◽  
Model System ◽  
Quintet State ◽  
Consistent Field ◽  
Self Consistent ◽  
Stabilizing Effect ◽  
Self Consistent Field ◽  
Preliminary Version

<div>Stochastic-CASSCF and DMRG procedures have been utilized to quantify the role of the electron correlation mechanisms that in a Fe-porphyrin model system are responsible for the differential stabilization of the triplet over the quintet state. Orbital entanglement diagrams and CI-coefficients of the wave function in a localised orbital basis allow for an effective interpretation of the role of charge-transfer configurations. A preliminary version of the <i>Stochastic Generalized Active Space Self-Consistent Field</i> method has been developed and is here introduced to further assess the pi-backdonation stabilizing effect.</div><div>By the new method excitations between metal and ligand orbitals can selectively be removed from the complete CI expansion. It is demonstrated that these excitations are key to the differential stabilization of the triplet, effectively leading to a quantitative measure of the correlation enhanced pi-backdonation.</div><div><br></div>

scholarly journals Chemical insights into the electronic structure of Fe(II) porphyrin using FCIQMC, DMRG, and generalized active spaces

2020 ◽  
Author(s):  
Oskar Weser ◽  
Leon Freitag ◽  
Kai Guther ◽  
Ali Alavi ◽  
Giovanni Li Manni
Keyword(s):  
Electron Correlation ◽  
Quantitative Measure ◽  
Model System ◽  
Quintet State ◽  
Consistent Field ◽  
Self Consistent ◽  
Stabilizing Effect ◽  
Self Consistent Field ◽  
Preliminary Version

<div>Stochastic-CASSCF and DMRG procedures have been utilized to quantify the role of the electron correlation mechanisms that in a Fe-porphyrin model system are responsible for the differential stabilization of the triplet over the quintet state. Orbital entanglement diagrams and CI-coefficients of the wave function in a localised orbital basis allow for an effective interpretation of the role of charge-transfer configurations. A preliminary version of the <i>Stochastic Generalized Active Space Self-Consistent Field</i> method has been developed and is here introduced to further assess the pi-backdonation stabilizing effect.</div><div>By the new method excitations between metal and ligand orbitals can selectively be removed from the complete CI expansion. It is demonstrated that these excitations are key to the differential stabilization of the triplet, effectively leading to a quantitative measure of the correlation enhanced pi-backdonation.</div><div><br></div>

scholarly journals Chemical insights into the electronic structure of Fe(II) porphyrin using FCIQMC, DMRG, and generalized active spaces

2020 ◽  
Author(s):  
Oskar Weser ◽  
Leon Freitag ◽  
Kai Guther ◽  
Ali Alavi ◽  
Giovanni Li Manni
Keyword(s):  
Electron Correlation ◽  
Quantitative Measure ◽  
Model System ◽  
Quintet State ◽  
Consistent Field ◽  
Self Consistent ◽  
Stabilizing Effect ◽  
Self Consistent Field ◽  
Preliminary Version

<div>Stochastic-CASSCF and DMRG procedures have been utilized to quantify the role of the electron correlation mechanisms that in a Fe-porphyrin model system are responsible for the differential stabilization of the triplet over the quintet state. Orbital entanglement diagrams and CI-coefficients of the wave function in a localised orbital basis allow for an effective interpretation of the role of charge-transfer configurations. A preliminary version of the <i>Stochastic Generalized Active Space Self-Consistent Field</i> method has been developed and is here introduced to further assess the pi-backdonation stabilizing effect.</div><div>By the new method excitations between metal and ligand orbitals can selectively be removed from the complete CI expansion. It is demonstrated that these excitations are key to the differential stabilization of the triplet, effectively leading to a quantitative measure of the correlation enhanced pi-backdonation.</div><div><br></div>

Photodynamic behavior of electronic coupling in a N-methylformamide dimer

2015 ◽  
Vol 17 (18) ◽  
pp. 12356-12364
Author(s):  
Martina Zámečníková ◽  
Dana Nachtigallová
Keyword(s):  
Perturbation Theory ◽  
Excited State ◽  
Electronic Coupling ◽  
Water Molecules ◽  
Complete Active Space ◽  
Active Space ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field

The role of the bridging water molecules has been studied during the excited state photodynamics of a N-methylformamide dimer in complex with water molecules employing the complete active space self-consistent field (CASSCF) and CAS perturbation theory (CASPT2) methods.

I. First Principles Cluster Calculations for the Electronic Structures of CuO7 Octahedron and CuO5 Pyramid

1997 ◽  
Vol 11 (32) ◽  
pp. 3733-3750 ◽  
Author(s):  
Akihiro Sano ◽  
Mikio Eto ◽  
Hiroshi Kamimura
Keyword(s):  
First Principles ◽  
Electronic Structures ◽  
Field Method ◽  
Strongly Correlated ◽  
Cluster Systems ◽  
Consistent Field ◽  
Cluster Calculations ◽  
Self Consistent ◽  
Self Consistent Field

In this paper we first describe the multi-configuration self-consistent field method with configuration interaction (MCSCF-CI) which is a variational method most suitable for strongly-correlated cluster systems. Then the calculated results of CuO 6 cluster embedded in hole-doped La 2-x Sr x CuO 4 and of CuO 4 cluster in the electron-doped Nd 2-x Ce x CuO 4 are reviewed. Finally the calculated results on the electronic structure of CuO 5 pyramid embedded in the insulating YBa 2 Cu 3 O 6 and superconducting YBa2Cu3O7 are newly presented. In the latter case we will clarify an important role of the Cu-O chain in the electronic and superconducting state of YBa2Cu3O7 .

Calculating Phase Diagrams of Polymer-Clay Mixtures by Combining Density Functional and Self-Consistent Field Theory

1999 ◽  
Vol 576 ◽  
Author(s):  
Anna C. Balazs ◽  
Chandralekha Singh ◽  
Valeriy V. Ginzburg
Keyword(s):  
Density Functional ◽  
Equilibrium Phase ◽  
Organic Modifiers ◽  
Functional Theory ◽  
Clay Particles ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Self Consistent Field Theory

ABSTRACTWe analyze the thermodynamics of polymer-clay mixtures within the framework of density functional theory (DFT). The interaction potential between clay particles is calculated using the self-consistent field (SCF) method and is strongly dependent on the length and density of grafted short-chain organic modifiers. By combining the DFT and SCF techniques, we determine the role of the grafted chains on the equilibrium phase behavior of the mixtures.

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