Mapped Finite Element Discrete Variable Representation

Efficient numerical solver for the SchrSdinger equation is very important in physics and chemistry. The finite element discrete variable representation （FE-DVR） was first proposed by Rescigno and Mc-Curdy [Phys. Rev. A 62, 032706 （2000）] for solving quantum-mechanical scattering problems. In this work, an FE-DVR method in a mapped coordinate was proposed to improve the efficiency of the original FE-DVR method. For numerical demonstration, the proposed approach is applied for solving the electronic eigenfunctions and eigenvalues of the hydrogen atom and vibrational states of the electronic state 3E＋ of the Cs2 molecule which has long-range interaction potential. The numerical results indicate that the numerical efficiency of the original FE-DVR has been improved much using our proposed mapped coordinate scheme.

Influence of Molecular Stacking Pattern on Excited State Dynamics of Copper Phthalocyanine Films

Photophysical processes occurring within organic semiconductors is important for designing and fabricating organic solar cells.Copper phthalocyanine(CuPc)is a typical electron acceptor.In this work,the triplet exciton lifetime is prolonged by altering the molecular stacking pattern of the CuPc film.For CuPc thin films,the excited state decays are mainly determined by the triplet-triplet annihilation process.The ultrafast transient absorption measurements indicate that the primary annihilation mechanism is one-dimensional exciton diffusion collision destruction.The decay kinetics show a clearly time-dependent annihilation rate constant withγ∝t^(-1/2).Annihilation rate constants are determined to beγ0=(2.87±0.02)×10^(-20)cm^(3)·s^(-1/2)and(1.42±0.02)×10^(-20)cm^(3)·s^(-1/2)for upright and lyingdown configurations,respectively.Compared to the CuPc thin film with an upright configuration,the thin film with a lying-down configuration shows longer exciton lifetime and higher absorbance,which are beneficial to organic solar cells.The results in this work have important implications on the design and mechanistic understanding of organic optoelectronic devices.

Internal Conversion Process of Chlorophyll a in Solvents in Femtosecond Pump-Probe Laser Fields

The internal conversion （IC） processes of chlorophyll a （chl-a） in solvents are studied based on the reduced density matrix theory. The IC times can be obtained by simulating the experimental fluorescence depletion spectra （FDS）. The calculated IC times of chl-a in ethyl acetate, tetrahydrofuran and dimethyl formamide are 141, 147, and 241 fs, respectively. The oscillation feature of the FDS results from the forward and backward transfer of the population between coupled electronic states. The effects of diabatic coupling between two electronic states on the IC time and the FDS are described. The influence of molecule-reservoir coupling on the IC time is also investigated.

The influence of collision energy on magnetically tuned^(6)Li-^(6)Li Feshbach resonance

The effect of collision energy on the magnetically tuned^(6)Li-^(6)Li Feshbach resonance(FR)is investigated theoretically by using the coupled-channel(CC)method for the collision energy ranging from 1μK·kBto 100μK·kB.At the collision energy of 1μK·kB,the resonance positions calculated are 543.152 Gs(s wave,the unit 1 Gs=10^(-4)T),185.109 Gs(p wave|ml|=0),and 185.113 Gs(p wave|ml|=1),respectively.The p-wave FR near 185 Gs exibits a doublet structure of 4 mGs,associated with dipole-dipole interaction.With the increase of the collision energy,it is found that the splitting width remains the same(4 mGs),and that the resonance positions of s and p waves are shifted to higher magnetic fields with the increase of collision energy.The variations of the other quantities including the resonance width and the amplitude of the total scattering section are also discussed in detail.The thermally averaged elastic rate coefficients at T=10,15,20,25 K are calculated and compared.

Antimony Selenide Thin Film Solar Cells with an Electron Transport Layer of Alq3

We fabricated Sb 2 Se 3 thin film solar cells using tris(8-hydroxy-quinolinato)aluminum(Alq 3)as an electron transport layer by vacuum thermal evaporation.Another small organic molecule of N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine(NPB)was used as a hole transport layer.We took ITO/NPB/Sb 2 Se 3/Alq 3/Al as the device architecture.An open circuit voltage(V o c)of 0.37 V,a short circuit current density(J s c)of 21.2 mA/cm 2,and a power conversion efficiency(PCE)of 3.79%were obtained on an optimized device.A maximum external quantum efficiency of 73%was achieved at 600 nm.The J s c,V o c,and PCE were dramatically enhanced after introducing an electron transport layer of Alq 3.The results suggest that the interface state density at Sb 2 Se 3/Al interface is decreased by inserting an Alq 3 layer,and the charge recombination loss in the device is suppressed.This work provides a new electron transport material for Sb 2 Se 3 thin film solar cells.