Points (i) and (ii) have been corrected and changed following to the referee’s amendments.
The authors have not carefully proofread this manuscript. Evidences of this includes (i) some errors in English typing, e.g. line 27 and line 119: it should be ‘plane wave …’ instead of ‘plan wave …’. Line between 33 and 34: it should be ‘The scattered positron and ejected electron …’ instead of ‘The scattered electron and ejected positron …’. (ii) There are repeated Bibliography like ref. 11 and ref. 31.