Record:   ATOM
Contains: the atomic coordinates for standard residues and the occupancy
          and temperature factor for each atom
Notes:	
ATOM records for proteins are listed from amino to carboxyl terminus.
Nucleic acid residues are listed from the 5' to the 3' terminus.
No ordering is specified for polysaccharides.
The list of ATOM records in a chain is terminated by a TER record.
If an atom is provided in more than one position, then a non-blank alternate
location indicator must be used. Within a residue, all atoms of a given
conformation are assigned the same alternate position indicator.
Additional atoms (modifying group) to side chains of standard residues are represented as a HET group
which is assigned its own residue name. The chainID, sequence
number, and insertion code assigned to the HET group is that of the
standard residue to which it is attached.
In some entries, the occupancy and temperature factor fields may be used for other quantities.
The segment identifier is a string of up to four (4) alphanumeric characters, left-justified, and may
include a space, e.g., CH86, A 1, NASE.

COLUMNS        DATA TYPE       CONTENTS                            
--------------------------------------------------------------------------------
 1 -  6        Record name     "ATOM  "
 7 - 11        Integer         Atom serial number.
13 - 16        Atom            Atom name.
17             Character       Alternate location indicator.
18 - 20        Residue name    Residue name.
22             Character       Chain identifier.
23 - 26        Integer         Residue sequence number.
27             AChar           Code for insertion of residues.
31 - 38        Real(8.3)       Orthogonal coordinates for X in Angstroms.
39 - 46        Real(8.3)       Orthogonal coordinates for Y in Angstroms.
47 - 54        Real(8.3)       Orthogonal coordinates for Z in Angstroms.
55 - 60        Real(6.2)       Occupancy.
61 - 66        Real(6.2)       Temperature factor (Default = 0.0).
73 - 76        LString(4)      Segment identifier, left-justified.
77 - 78        LString(2)      Element symbol, right-justified.
79 - 80        LString(2)      Charge on the atom.

Example: 
         1         2         3         4         5         6         7         8
12345678901234567890123456789012345678901234567890123456789012345678901234567890
ATOM    145  N   VAL A  25      32.433  16.336  57.540  1.00 11.92      A1   N
ATOM    146  CA  VAL A  25      31.132  16.439  58.160  1.00 11.85      A1   C
ATOM    147  C   VAL A  25      30.447  15.105  58.363  1.00 12.34      A1   C
ATOM    148  O   VAL A  25      29.520  15.059  59.174  1.00 15.65      A1   O
ATOM    149  CB AVAL A  25      30.385  17.437  57.230  0.28 13.88      A1   C
ATOM    150  CB BVAL A  25      30.166  17.399  57.373  0.72 15.41      A1   C
ATOM    151  CG1AVAL A  25      28.870  17.401  57.336  0.28 12.64      A1   C
ATOM    152  CG1BVAL A  25      30.805  18.788  57.449  0.72 15.11      A1   C
ATOM    153  CG2AVAL A  25      30.835  18.826  57.661  0.28 13.58      A1   C
ATOM    154  CG2BVAL A  25      29.909  16.996  55.922  0.72 13.25      A1   C
