# Chemestry: molecules¶

Author(s): Joren Retel & Peter Koppatz Chemestry, molecules

## Objectives¶

 Atoms and molecules – an exiting use case for 3D. With this material it is possible to create molecules, other experiments outside of chemistry and just for fun. A script is guiding you to create molecules or other objects.

## Instructions¶

1. Download: Zipfile with example data (PDB)
2. Open the blend file and have a look at the examples.
3. Add new molecules to the collection.
4. Let students construct a molecule from a given set of atoms.
5. Working with atoms should be fun, how about constructing a name from a set of atoms.

If a real molecule is intergrated in the name, as student can earn some extra points.

Hint: All mentioned files are available as a collection within the blend-file.

## PDB-Format¶

We use the structure of a PDB-File. The documentation about the PDB format is available at:

or the short version in the following table:

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.

Part of a PDB file:

         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


## Simple version or teaching¶

To experiment with this file format we only need the coordinates an the type of atom. So the following simpler structure remains (a water molecule in this example):

########## PDB-Struktur(vereinfacht) ##########
# H20 (Wasser, Water)
ATOM                            -0.544  -0.257  -0.228                       H
ATOM                             0.391   0.456   0.228                       H
ATOM                            -0.332   0.44   -0.016                       O


Important for the representation is the use of different diameters and colors for each type of atom:

Atom Diameter Color
Hydrogen 0,32 blue
Carbon 0,91 green
Knitted fabric 0,75 blue
Phospor 1,06 red
Oxygen 0,73 red
unknown Atom 1,0 black

## Content of the Blender file¶

• 01 Introduction (listing of all possibilities)
• 02 PDB data structure (with examples, used by the standard)