Modelling the bacterial photosynthetic reaction center. VI. Use of density-functional theory to determine the nature of the vibronic coupling between the four lowest-energy electronic states of the special-pair radical cation

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.

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Research Optical Characteristics of H2S Molecule Adsorption on Agn (n=2,4,6) Clusters

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.321-324.499 ◽

2013 ◽

Vol 321-324 ◽

pp. 499-502

Author(s):

Hong Zhou ◽

Jun Feng Wang ◽

Jun Qing Wen ◽

Wei Bin Cheng ◽

Jun Fei Wang

Keyword(s):

Density Functional Theory ◽

Infrared Spectrum ◽

Density Functional ◽

Global Minimum ◽

Electronic States ◽

Binding Energies ◽

Optical Characteristics ◽

Functional Theory ◽

Calculation Results ◽

Planar Geometries

Density-functional theory has been used to calculate the energetically global-minimum geometries and electronic states of AgnH2S (n=2, 4, 6) clusters. The lowest-energy structures of Ag2, Ag4, Ag6, Ag2H2S, Ag4H2S and Ag6H2S clusters were obtained, respectively. The calculation results show that the lowest-energy structures of Ag2, Ag4and Ag6clusters are planar geometries. The binding energies of Agn(n=2, 4, 6) clusters are gradually increasing in our calculations. Compare the infrared spectrum peaks of Ag4cluster with that of Ag6cluster, which show that the peaks shift to shortwave. After adsorption, we found that the peaks shift to shortwave by comparison.

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Density functional theory study on the atomic structure and electronic states of Cu(100) (2×22)R45°-O surface

Acta Physica Sinica ◽

10.7498/aps.54.5350 ◽

2005 ◽

Vol 54 (11) ◽

pp. 5350

Author(s):

Cai Jian-Qiu ◽

Tao Xiang-Ming ◽

Chen Wen-Bin ◽

Zhao Xin-Xin ◽

Tan Ming-Qiu

Keyword(s):

Density Functional Theory ◽

Atomic Structure ◽

Density Functional ◽

Electronic States ◽

Density Functional Theory Study ◽

Functional Theory

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Detailed features of the surface electronic states of K/Cu(111) by density functional theory

Physical Review B ◽

10.1103/physrevb.81.165444 ◽

2010 ◽

Vol 81 (16) ◽

Cited By ~ 6

Author(s):

S. Achilli ◽

M. I. Trioni ◽

G. P. Brivio

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Electronic States ◽

Functional Theory

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Width-dependent structural stability and magnetic properties of monolayer zigzag MoS2 nanoribbons

Modern Physics Letters B ◽

10.1142/s0217984917500178 ◽

2017 ◽

Vol 31 (03) ◽

pp. 1750017 ◽

Cited By ~ 7

Author(s):

Yan-Ni Wen ◽

Peng-Fei Gao ◽

Xi Chen ◽

Ming-Gang Xia ◽

Yang Zhang ◽

...

Keyword(s):

Density Functional Theory ◽

Magnetic Properties ◽

Structural Stability ◽

Magnetic Moment ◽

First Principles ◽

Density Functional ◽

Electronic States ◽

Two Dimensional ◽

Functional Theory ◽

Proportional Relationship

First-principles study based on density functional theory has been employed to investigate width-dependent structural stability and magnetic properties of monolayer zigzag MoS2 nanoribbons (ZZ-MoS2 NRs). The width N = 4–6 (the numbers of zigzag Mo–S chains along the ribbon length) are considered. The results show that all studied ZZ-MoS2 NRs are less stable than two-dimensional MoS2 monolayer, exhibiting that a broader width ribbon behaves better structural stability and an inversely proportional relationship between the structural stability (or the ribbon with) and boundary S–Mo interaction. Electronic states imply that all ZZ-MoS2 NRs exhibit magnetic properties, regardless of their widths. Total magnetic moment increases with the increasing width N, which is mainly ascribed to the decreasing S–Mo interaction of the two zigzag edges. In order to confirm this reason, a uniaxial tension strain is applied to ZZ-MoS2 NRs. It has been found that, with the increasing tension strain, the bond length of boundary S–Mo increases, at the same time, the magnetic moment increases also. Our results suggest the rational applications of ZZ-MoS2 NRs in nanoelectronics and spintronics.

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Density Functional Study of H2S Adsorption on Small Agn (n = 1–5)

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.634-638.47 ◽

2013 ◽

Vol 634-638 ◽

pp. 47-51 ◽

Cited By ~ 1

Author(s):

Jun Qing Wen ◽

A Ping Yang ◽

Guo Xiang Chen ◽

Chen Jun Zhang

Keyword(s):

Density Functional Theory ◽

Binding Energy ◽

Density Functional ◽

Global Minimum ◽

Electronic States ◽

Functional Study ◽

Functional Theory ◽

Energy Gaps ◽

Single Fold ◽

Homo And Lumo

The global-minimum geometries and electronic states of AgnH2S (n=1-5) clusters have been calculated using density-functional theory. Our calculations predicate that the stable geometries of AgnH2S clusters can be got by directly adding the H2S molecule on different site of Agn clusters, Agn (n=1-5) clusters would like to bond with sulfur atom and the H2S molecule is partial to hold the top location and single fold coordination site in the clusters. After adsorption, the structures of Agn clusters and H2S molecule keep the original structures and are only distorted slightly. The averaged binding energy reveals that adsorption of H2S molecule can strengthen the stabilities of AgnH2S clusters. The second difference in energy and the energy gaps between the HOMO and LUMO of Agn and AgnH2S have been studied.

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