Description of electron transfer in the ground and excited states of organic donor–acceptor systems by single-reference and multi-reference density functional methods

2014 ◽  
Vol 141 (12) ◽  
pp. 124123 ◽  
Author(s):  
Michael Filatov
Keyword(s):  
Electron Transfer ◽  
Excited States ◽  
Density Functional ◽  
Density Functional Methods ◽  
Functional Methods ◽  
Donor Acceptor

scholarly journals The vacuum ultraviolet spectrum of cyclohepta-1, 3, 5-triene: Analysis of the singlet and triplet excited states by ab initio and density functional methods

2020 ◽  
Vol 153 (5) ◽  
pp. 054301
Author(s):  
Michael H. Palmer ◽  
Søren Vrønning Hoffmann ◽  
Nykola C. Jones ◽  
Marcello Coreno ◽  
Monica de Simone ◽  
...  
Keyword(s):  
Ab Initio ◽  
Excited States ◽  
Density Functional ◽  
Vacuum Ultraviolet ◽  
Ultraviolet Spectrum ◽  
Density Functional Methods ◽  
Functional Methods ◽  
Triplet Excited States

Excited states of analogue models of M-bacteriochlorophylls (M = Mg, Zn) in the photosynthetic reaction center: a time-dependent density functional theory study

2002 ◽  
Vol 06 (10) ◽  
pp. 617-625 ◽  
Author(s):  
Yoichi Yamaguchi
Keyword(s):  
Electron Transfer ◽  
Excited States ◽  
Density Functional ◽  
Photosynthetic Reaction Center ◽  
Excited Electron ◽  
Time Dependent ◽  
Analogue Model ◽  
Functional Theory ◽  
Special Pair ◽  
Dependent Density

Using time-dependent density functional theory (TDDFT), the excited states of the analogue model Mg -bacteriochlorophyll b - imidazole ( BChl -Im) dimer (P) for a special pair in the photosynthetic reaction center (RC) of Rhodopseudomonas (Rps.) viridis were examined. The calculated low-lying excited states and optimal geometries are in good agreement with experimental data. The order of the lowest unoccupied molecular orbital (LUMO) energies of P, the monomeric "accessory" BChl -Im (B), and bacteriopheophytin b ( H ) indicates the possibility of the light-induced electron transfer from P to H via B. The Im ligand of B destabilizes Goutermann's four-orbitals of BChl by 0.3-0.4 eV. With no energetic difference in the LUMOs between H and BChl , the Im ligands of P and B play an important role in providing a greater energetic gradient to the LUMOs along with the pathway for the excited-electron transfer in RC, resulting in the reduced reverse electron transfer from H to P (via B). Thus it is expected that the asymmetric Mg -Im interactions will directly affect the pathway of the excited-electron transfer. Using the deformed heterodimer (P') formed by the BChl halves with and without Im as the primary donor model, its cation radical P'+ was calculated as to whether the experimental asymmetric spin-density distribution can reproduce. The excited states of the analogue model Zn - BChl -Im dimer for a special pair in RC of the recently discovered Acidiphilium rubrum were also examined for a comparison with P.

Substituent effect on N–H bond dissociation enthalpies of carbamates: a theoretical study

2015 ◽  
Vol 93 (3) ◽  
pp. 279-288 ◽  
Author(s):  
Rupinder preet Kaur ◽  
Damanjit Kaur ◽  
Ritika Sharma
Keyword(s):  
Substituent Effect ◽  
Density Functional ◽  
Theoretical Study ◽  
Natural Bond Orbital ◽  
Stabilization Energy ◽  
Isodesmic Reactions ◽  
Bond Dissociation ◽  
Density Functional Methods ◽  
Functional Methods ◽  
Orbital Analysis

The present investigation deals with the study of the N–H bond dissociation enthalpies (BDEs) of the Y-substituted (NH2-C(=X)Y-R) and N-substituted ((R)(H)NC(=X)YH) carbamates (X, Y = O, S, Se; R = H, CH3, F, Cl, NH2), which have been evaluated using ab initio and density functional methods. The variations in N−H BDEs of these Y-substituted and N-substituted carbamates as the effect of substituent have been understood in terms of molecule stabilization energy (ME) and radical stabilization energy (RE), which have been calculated using the isodesmic reactions. The natural bond orbital analysis indicated that the electrodelocalization of the lone pairs of heteroatoms in the molecules and radicals affect the ME and RE values depending upon the type and site of substitution (whether N- or Y-). The variations in N−H BDEs depend upon the combined effect of molecule stabilization and radical stabilization by the various substituents.

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