New Energy-Based Decoherence Correction Approaches for Trajectory Surface Hopping

Inspired by the branching corrected surface hopping(BCSH)method[J.Xu and L.Wang,J.Chem.Phys.150,164101(2019)],we present two new decoherence time formulas for trajectory surface hopping.Both the proposed linear and exponential formulas characterize the decoherence time as functions of the energy difference between adiabatic states and correctly capture the decoherence effect due to wave packet reflection as predicted by BCSH.The relevant parameters are trained in a series of 200 diverse models with different initial nuclear momenta,and the exact quantum solutions are utilized as references.As demonstrated in the three standard Tully models,the two new approaches exhibit significantly higher reliability than the widely used counterpart algorithm while holding the appealing efficiency,thus promising for nonadiabatic dynamics simulations of general systems.

Surface and intrinsic contributions to extinction properties of ZnSe quantum dots

This work studies extinction properties of ZnSe quantum dots terminated with either Se-surface or Zn-surface(Se-ZnSe or Zn-ZnSe QDs).In addition to commonly observed photoluminescence quenching by anionic surface sites,Se-ZnSe QDs are found to show drastic signatures of Se-surface states in their UV-visible(Vis)absorption spectra.Similar to most QDs reported in literature,monodisperse Zn-ZnSe QDs show sharp absorption features and blue-shifted yet steep absorption edge respect to the bulk bandgap.However,for monodisperse Se-ZnSe QDs,all absorption features are smeared and a low-energy tail is identified to extend to an energy window below the bulk ZnSe bandgap.Along increasing their size,a cyclic growth of ZnSe QDs switches their surface from Zn-terminated to Se-terminated ones,which confirms that the specific absorption signatures are reproducibly repeated between those of two types of the QDs.Though the extinction coefficients per unit of Se-ZnSe QDs are always larger than those of Zn-ZnSe QDs with the same size,both of them approach the same bulk limit.In addition to contribution of the lattice,extinction coefficients per nanocrystal of Zn-ZnSe QDs show an exponential term against their sizes,which is expected for quantum-confinement enhancement of electron-hole wavefunction overlapping.For Se-ZnSe QDs,there is the third term identified for their extinction coefficients per nanocrystal,which is proportional to the square of size of the QDs and consistent with surface contribution.