  Search for one dimensional (1D) van der Waals materials has become an urgent
need to meet the demand as building blocks for high performance, miniaturized,
lightweight device applications. Polyyne, a 1D atomic chain of carbon is the
thinnest and strongest allotrope of carbon, showing promising applications in
new generation low dimensional devices due to the presence of a band gap. A
system of two carbon chains held together by van der Waals interaction has been
theoretically postulated and shows band gap tunability under structural changes
which finds applications in the realms of resistive switching and spintronics.
In this study, we use first principles Density Functional Theory (DFT) to show
a sharp semiconductor to metal transition along with the emergence of an
asymmetry in the spin polarized density of states for single and two polyyne
chains under a transverse electric field. The thermodynamic stability of the
system has been substantiated through the utilization of Ab Initio Molecular
Dynamics (AIMD) simulations, phonon dispersion curve analyses, and formation
energy calculations. Furthermore, in addition to its dynamic stability
assessment, phonon calculations have served to identify Raman active
vibrational modes which offers an invaluable non-destructive experimental
avenue for discerning electronic phase transitions in response to an applied
electric field. Our study presents a predictive framework for the prospective
utilization of one and two polyyne chains in forthcoming flexible
nano-electronic and spintronic devices. The future prospects of the system are
contingent upon advancements in nano-electronics fabrication techniques and the
precise construction of circuitry for harnessing spin-related applications.
