foreach my $ref (keys %$data){
   if($data->{$ref}->type eq 'ATOM'){
      my $atom = $data->{$ref}->atom;
      $self->{$ref}{atoms} = $atom;
      $self->{$ref}{'residues'} = $atom->resNumber;
      $self->{$ref}{'chain'} = $atom->chainId;
   }
}