Geometry Conversion¶

CHAMP uses a specific format for defining molecular geometry in the input file.

Input Formats¶

The geometry can be defined in the load molecule section, a separate file, or using an inline block.

1. Standard Format (Automatic Valence)¶

For all-electron calculations, CHAMP automatically assigns valence charges.

load molecule
    3
    H2O molecule
    O  0.000000  0.000000  0.000000
    H  0.000000  1.430428  1.107230
    H  0.000000 -1.430428  1.107230
end

2. Explicit Valence (For ECPs)¶

When using Effective Core Potentials (ECPs), you must specify the number of valence electrons for each atom. This is the 5^th column in the geometry file.

load molecule
    3
    H2O with ECP on Oxygen (6 valence e-)
    O  0.000000  0.000000  0.000000  6.0
    H  0.000000  1.430428  1.107230  1.0
    H  0.000000 -1.430428  1.107230  1.0
end

3. Inline Block¶

For small molecules, you can use the %block molecule syntax directly in the input file.

%block molecule
    3
    H2O inline
    O  0.000000  0.000000  0.000000
    H  0.000000  1.430428  1.107230
    H  0.000000 -1.430428  1.107230
%endblock

Using TREXIO¶

If you are using TREXIO, the geometry is automatically read from the TREXIO file.

load trexio  'my_molecule.trexio'

Detailed Reference¶

For a complete description of geometry formats and options, see the Molecular Geometry page.