  Expansive open Fermi arcs covering most of the surface Brillouin zone (SBZ)
are desirable for detection and control of many topological phenomena, but so
far has been only reported for Kramers-Weyl points, or unconventional chiral
fermions, pinned at time-reversal invariant momentum in chiral materials. Here
using first-principles band structure calculations, we show that for
conventional Weyl points in ZrTe5 with the chirality of +1/-1 near the BZ
center at general momentum induced by one of the infrared phonons, the second
lowest B1u mode for breaking inversion symmetry, they can also form expansive
open Fermi arcs across the SBZ boundary to occupy most of the SBZ when
projected on (001) surface. We reveal that such expansive open Fermi arcs are
evolved from the topological surface states that connect multiple surface Dirac
points on the (001) surface of the topological insulator phases without lattice
distortion in ZrTe5. Furthermore, we find that the connectivity of the induced
open Fermi arcs can be changed by the magnitude of the lattice distortion of
this infrared phonon mode. Thus, we propose that using coherent optical phonon
to modulate lattice parameters can offer ways to induce novel topological
features including expansive open Fermi arcs and dynamically control Fermi arcs
connectivity in ZrTe5.
