We have presented a theoretical study on the PDWS via TDDFT/Ehrenfest nonadiabatic dynamics. By comparing the calculated results of four model systems: H 2 O and Au 20 @H 2 O separately interacting with the laser field and the near fields, we clearly reveal the microscopic mechanism of PDWS and the interface electron transfer, and the correlation of the reaction rate with the laser field frequency and intensity, the NP's sizes, and the field's spatial distribution. A multiscale scheme has been applied to describe PDWS dynamics. For H 2 O and Au 20 @H 2 O systems, its electronic degrees of freedom were treated quantum mechanically within the real-space real-time implementation of TDDFT, while their ions were handled classically. For the system with larger sized NP, we divided this NP into Au 20 + residue, where Au 20 was described by TDDFT and the truncated NP was described by FDTD.