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Optimizing Conical Intersections by Spin-Flip Density Functional Theory: Application to Ethylene

TitleOptimizing Conical Intersections by Spin-Flip Density Functional Theory: Application to Ethylene
Publication TypeJournal Article
Year of Publication2009
AuthorsMinezawa N, Gordon MS
Journal TitleJournal of Physical Chemistry A
Volume113
Pages12749-12753
Date Published11/19
ISBN Number1089-5639
Accession NumberISI:000271583100001
Keywordsab-initio, BASIS-SETS, diradicals, excited-states, molecular-dynamics, photochemistry, photodynamics, photoisomerization, potential-energy surface, wave-functions
Abstract

Conical intersections (CIs) of ethylene have been successfully determined using spin-flip density functional theory (SFDFT) combined with a penalty-constrained optimization method. We present in detail three structures, twisted-pyramidalized, hydrogen-migrated, and ethylidene CIs. In contrast to the linear response time-dependent density functional theory, which predicts a purely twisted geometry without pyramidalization as the S, global minimum, SFDFT gives a pyramidalized structure. Therefore, this is the first correct optimization of CI. points of twisted ethylene by the DFT method. The calculated energies and geometries are in good agreement with those obtained by the multireference configuration interaction (MR-CI) method and the multistate formulation of second-order multireference perturbation theory (MS-CASPT2).
URL<Go to ISI>://000271583100001
DOI10.1021/Jp908032x
Alternate JournalJ Phys Chem A