subroutine real HBONDS_CUT
!ATOM_NEIGH.COM:
! return

key xxnn select ( wat .or. xxx ) .and. atom name O* end

key at_o select atom name O* .and. .not. xxnn end
key at_n select atom name N* end

key to_o select around key at_o from xxnn dist HBONDS_CUT end
key to_n select around key at_n from xxnn dist HBONDS_CUT end

key to_o_n sele to_o .or. to_n end
key to_o2 select around key to_o_n from xxnn dist HBONDS_CUT end

key out select .not ( to_o2 .or. to_o_n ) .and. xxnn end
delete atom select by residue out .a .not 3sigma end

key xxnn drop
key at_o drop
key at_n drop
key to_o drop
key to_n drop
key to_o_n drop
key to_o2 drop
return