use sequential solver in special case of mpi_grid
use sequential solver in special case of mpi_grid

toxa81/sirius,electronic-structure/sirius,electronic-structure/sirius,toxa81/sirius,toxa81/sirius,electronic-structure/sirius,electronic-structure/sirius,electronic-structure/sirius,electronic-structure/sirius,electronic-structure/sirius,toxa81/sirius,toxa81/sirius,toxa81/sirius