new index atom name original index 1 C 6 2 C 10 3 C 11 4 C 8 5 C 7 6 C 9 7 N 4 8 N 5 9 N 3 10 O 1 11 O 2 12 H 16 13 H 17 14 H 19 15 H 20 16 H 18 17 H 14 18 H 15 19 H 13 20 H 12