导师要找到说过The (2 x 2 x 2) supercell of cubic MAPbI3 is essentially the (√2 x √2 x 1) of tetragonal unit cell. Therefore, the supercell of cubic MAPbI3 will transform to the tetragonal phase.这个结论的文献,我自己也不记得了,有没有老哥刚好在看或者记得的这篇的,求求了