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Research output: Thesis › Doctoral Thesis
Research output: Thesis › Doctoral Thesis
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TY - BOOK
T1 - Development of Density Functional Methods for Electronic Excited States and the Influence of Molecular Structure on Electronic Excited States
AU - Fletcher, Peter
PY - 2021
Y1 - 2021
N2 - An extensive assessment of six density functional approximations has beenundertaken, each of these approximations have their own merits and faults.Range separated hybrids are the best performing for excited state propertiesof those approximations assessed.There has been an attempt to generate an attenuated form of PBE(CAM-PBE) which initially had issues which were investigated in detailregarding the dependence of Hartree–Fock exchange energy on approximation performance. This attenuated form of PBE had similar performance toCAM-B3LYP.The development of a set of benchmark data for excited state geometriesand emission energies was undertaken with a wide range of organic moleculesdue to the lack of such benchmark data existing currently. This meansthe accuracy of density functional approximations for calculation of suchproperties is unknown so there is a clear need for this benchmark data tobe developed and used to assess the accuracy of these approximations.The benchmark data for excited state geometries and emission energieswas used to assess the performance of a range of density functional approximations for these properties. This assessment has suggested that there are issues when applying current density functional approximations away fromthe ground state where they have been tuned and optimised. This suggeststhat there may be some merit in developing specialised density functionalapproximations for the calculation of excited state properties.The existing density functional approximations have been used to assist with experimental investigations of porous polymers and in explainingthe excited state properties of these polymers. This was done using modelsystems and has enabled a deeper understanding of the experimental observations
AB - An extensive assessment of six density functional approximations has beenundertaken, each of these approximations have their own merits and faults.Range separated hybrids are the best performing for excited state propertiesof those approximations assessed.There has been an attempt to generate an attenuated form of PBE(CAM-PBE) which initially had issues which were investigated in detailregarding the dependence of Hartree–Fock exchange energy on approximation performance. This attenuated form of PBE had similar performance toCAM-B3LYP.The development of a set of benchmark data for excited state geometriesand emission energies was undertaken with a wide range of organic moleculesdue to the lack of such benchmark data existing currently. This meansthe accuracy of density functional approximations for calculation of suchproperties is unknown so there is a clear need for this benchmark data tobe developed and used to assess the accuracy of these approximations.The benchmark data for excited state geometries and emission energieswas used to assess the performance of a range of density functional approximations for these properties. This assessment has suggested that there are issues when applying current density functional approximations away fromthe ground state where they have been tuned and optimised. This suggeststhat there may be some merit in developing specialised density functionalapproximations for the calculation of excited state properties.The existing density functional approximations have been used to assist with experimental investigations of porous polymers and in explainingthe excited state properties of these polymers. This was done using modelsystems and has enabled a deeper understanding of the experimental observations
KW - Density function theory (DFT)
KW - DENSITY FUNCTIONALS
KW - TDDFT
KW - ELECTRONIC EXCITATIONS
KW - Electronic excited states
KW - POROUS MATERIALS
KW - Benchmarking
KW - Benchmark datasets
KW - MOLECULAR STRUCTURE
KW - Electronic structure
KW - Quantum chemistry
KW - Quantum chemical calculations
KW - Theoretical chemistry
U2 - 10.17635/lancaster/thesis/1388
DO - 10.17635/lancaster/thesis/1388
M3 - Doctoral Thesis
PB - Lancaster University
ER -