Accurate calculation of spin-state energy gaps in Fe(III) Spin-Crossover systems using Density Functional Methods

2021 ◽  
Author(s):  
Daniel Vidal ◽  
Jordi Ribas-Ariño ◽  
Jordi Cirera
Keyword(s):  
Spin State ◽  
Density Functional ◽  
Spin Crossover ◽  
State Energy ◽  
Accurate Calculation ◽  
Density Functional Methods ◽  
Functional Methods ◽  
Energy Gaps

Fe(III) complexes are receiving ever-increasing attention as spin crossover (SCO) systems because they are usually air stable, as opposed to Fe(II) complexes, which are prone to oxidation. Here, we present...

Free Energy of Spin-Crossover Complexes Calculated with Density Functional Methods

2001 ◽  
Vol 40 (9) ◽  
pp. 2201-2203 ◽  
Author(s):  
Hauke Paulsen ◽  
Lars Duelund ◽  
Heiner Winkler ◽  
Hans Toftlund ◽  
Alfred X. Trautwein
Keyword(s):  
Free Energy ◽  
Density Functional ◽  
Spin Crossover ◽  
Density Functional Methods ◽  
Functional Methods ◽  
Spin Crossover Complexes

scholarly journals Localized Active Space Pair-Density Functional Theory

2021 ◽  
Author(s):  
Riddhish Pandharkar ◽  
Matthew R. Hermes ◽  
Christopher J. Cramer ◽  
Donald G. Truhlar ◽  
Laura Gagliardi
Keyword(s):  
Density Functional Theory ◽  
Wave Function ◽  
Spin State ◽  
Density Functional ◽  
State Energy ◽  
Correlation Energy ◽  
Functional Theory ◽  
Active Space ◽  
Energy Gaps ◽  
Pair Density

Accurate quantum chemical methods for the prediction of spin-state energy gaps for strongly correlated systems are computationally expensive and scale poorly with the size of the system. This makes calculations for many experimentally interesting molecules impractical even with abundant computational resources. In previous work, we have shown that the localized active space (LAS) self-consistent field (SCF) method is an efficient way to obtain multi-configuration SCF wave functions of comparable quality to the corresponding complete active space (CAS) ones. To obtain quantitative results, a post-SCF method is needed to estimate the complete correlation energy. One such method is multiconfiguration pair-density functional theory (PDFT), which calculates the energy based on the density and on-top pair density obtained from a multiconfiguration wave function. In this work we introduce localized-active-space pair-density functional theory, which uses a LAS wave function for subsequent PDFT calculations. The method is tested for computing spin-state energy gaps in conjugated organic molecules and bimetallic compounds and is shown to give results within 0.05 eV of the corresponding CAS-PDFT results at a significantly lower cost.

scholarly journals Localized Active Space Pair-Density Functional Theory

2021 ◽  
Author(s):  
Riddhish Pandharkar ◽  
Matthew R. Hermes ◽  
Christopher J. Cramer ◽  
Donald G. Truhlar ◽  
Laura Gagliardi
Keyword(s):  
Density Functional Theory ◽  
Wave Function ◽  
Spin State ◽  
Density Functional ◽  
State Energy ◽  
Correlation Energy ◽  
Functional Theory ◽  
Active Space ◽  
Energy Gaps ◽  
Pair Density

Accurate quantum chemical methods for the prediction of spin-state energy gaps for strongly correlated systems are computationally expensive and scale poorly with the size of the system. This makes calculations for many experimentally interesting molecules impractical even with abundant computational resources. In previous work, we have shown that the localized active space (LAS) self-consistent field (SCF) method is an efficient way to obtain multi-configuration SCF wave functions of comparable quality to the corresponding complete active space (CAS) ones. To obtain quantitative results, a post-SCF method is needed to estimate the complete correlation energy. One such method is multiconfiguration pair-density functional theory (PDFT), which calculates the energy based on the density and on-top pair density obtained from a multiconfiguration wave function. In this work we introduce localized-active-space pair-density functional theory, which uses a LAS wave function for subsequent PDFT calculations. The method is tested for computing spin-state energy gaps in conjugated organic molecules and bimetallic compounds and is shown to give results within 0.05 eV of the corresponding CAS-PDFT results at a significantly lower cost.

Energy Gaps of α,α‘-Substituted Oligothiophenes from Semiempirical, Ab Initio, and Density Functional Methods

2000 ◽  
Vol 104 (35) ◽  
pp. 8256-8262 ◽  
Author(s):  
Marcos A. De Oliveira ◽  
Hélio A. Duarte ◽  
Jean-Michel Pernaut ◽  
Wagner B. De Almeida
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Density Functional Methods ◽  
Functional Methods ◽  
Energy Gaps
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