  Electromagnetic particle-in-cell (PIC) codes are widely used to perform
computer simulations of a variety of physical systems, including fusion
plasmas, astrophysical plasmas, plasma wakefield particle accelerators, and
secondary photon sources driven by ultra-intense lasers. In a PIC code,
Maxwell's equations are solved on a grid with a numerical method of choice.
This article focuses on pseudo-spectral analytical time-domain (PSATD)
algorithms and presents a novel hybrid PSATD PIC scheme that combines the
respective advantages of standard nodal and staggered methods. The novelty of
the hybrid scheme consists in using finite-order centering of grid quantities
between nodal and staggered grids, in order to combine the solution of
Maxwell's equations on a staggered grid with the deposition of charges and
currents and the gathering of electromagnetic forces on a nodal grid. The
correctness and performance of the novel hybrid scheme are assessed by means of
numerical tests that employ different classes of PSATD equations in a variety
of physical scenarios, ranging from the modeling of electron-positron pair
creation in vacuum to the simulation of laser-driven and particle beam-driven
plasma wakefield acceleration. It is shown that the novel hybrid scheme offers
significant numerical and computational advantages, compared to purely nodal or
staggered methods, for all the test cases presented.
