BSTRACTDensity functional theory with Hubbard U correction is employed to study the polaron in rutile under external electric fields. It is found that electric-field-induced displacements of the ions enhance the sampling of the polaron configurations

which is helpful to find the most stable structure among local minima. More importantly

we demonstrate that with increasing electric field

the polaron may vanish

i.e. the excess electron can dissociate from the bounded Ti

3+

and this process is reversible with the opposite electric field. The present findings shed light on more complex mechanisms for the polaron-related conductivity in oxides and corresponding devices.

Impact statement

The first

ab initio

demonstration of the polaron dynamics under electric fields provides a complete picture of the polaron in rutile

deepening the understanding of the conductivity in the oxides.