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Full-Text Articles in Physical Sciences and Mathematics

An Ab Initio Investigation Of The Stabilization Of Selected Β-Substituted Ethyl Cations And Α-Substituted Methyl Cations, Julia C. White, Robert J. Cave, Ernest R. Davidson Jan 1988

An Ab Initio Investigation Of The Stabilization Of Selected Β-Substituted Ethyl Cations And Α-Substituted Methyl Cations, Julia C. White, Robert J. Cave, Ernest R. Davidson

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In this study, we calculate the stabilization of β-substituted ethyl cations (R = H, Li, BeH, BH_2, CH_3, NH_2, OH, F, Na, MgH, AlH_2, SiH_3, PH_2, SH, Cl) and α-substituted methyl cations (R = H, Li, CH_3, NH_2, OH, F, Na, SiH_3, PH_2, SH, Cl) in order to obtain a relationship between the nature of the substituent and the degree of stabilization of the cation. Results show that the stabilization energy is related to the electronegativity of the β substituents, but not the α substituents. The rotational barrier of the β-substituted ethyl cation is linearly related to the Mulliken population …


Ab Initio Investigation Of Several Low-Lying States Of All-Trans Octatetraene, Robert J. Cave, Ernest R. Davidson Jan 1988

Ab Initio Investigation Of Several Low-Lying States Of All-Trans Octatetraene, Robert J. Cave, Ernest R. Davidson

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The results of ab initio calculations that examine vertical and nonvertical transitions to several low-lying states of all-trans-octatetraene are presented. It is found that the lowest vertical excitation is to a valence π → π* ¹B_u state, and the nominally doubly excited 2¹A_g state occurs approximately 0.4 eV higher at the geometry of the ground state. Using estimated excited-state equilibrium geometries, we find that the 2¹A_g state is indeed the lowest singlet excited state, having a 0-0 tarnsition energy of 4.15 eV. The 0-0 transition energy for the 1¹B_u state is calculated to be 4.56 eV. The present results …


A Theoretical Investigation Of Several Low-Lying States Of Trans, Trans-1,3,5-Hexatriene, Robert J. Cave, Ernest R. Davidson Jan 1988

A Theoretical Investigation Of Several Low-Lying States Of Trans, Trans-1,3,5-Hexatriene, Robert J. Cave, Ernest R. Davidson

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Results from ab initio calculations concerning several low-lying electronic states of trans,trans-1,3,5-hexatriene are presented and compared with experimental and previous theoretical results. The lowest excited singlet state is predicted to be the ¹B_u state, having essentially valencelike π → π* character. The nominally doubly excited 2¹A_g state is found to lie approximately 0.6-0.9 eV above the 1¹B_u state. Results are also presented for several Rydberg states. The implications of the present results for current parametrizations of semiempirical π molecular orbital schemes are discussed.