From sketch to a vibe-qc calculation input

Prepare an ethanol geometry and a gas-phase B3LYP/def2-SVP single-point input for vibe-qc. This is a small example of the preparation workflow, not a method recommendation for every chemical problem. Writing the input requires only vibe-sketch; executing it requires a working vibe-qc installation.

Generate the geometry

1. Open the ethanol document from Your first molecule, or create a new document and import CCO through Import ▾ → SMILES….

2. Check C2H6O, charge 0, and multiplicity 1 in the species card.

3. Click Generate 3D. The species’ 3D row should now identify the geometry method and 9 atoms: three heavy atoms and six hydrogens. Read any reported warnings before continuing.

The structure comes from distance geometry followed by a force-field optimization. It is a starting geometry, not the result of the requested quantum-chemical calculation. 3D structures describes conformers, stereochemistry checks and force-field limitations.

Choose the input settings

In Inputs, set the fields explicitly so an earlier saved choice does not change the example:

Field	Value
program	vibe-qc (script)
task	single point
method	B3LYP
dispersion	none
basis	def2-SVP
RI	none
solvent	gas phase
processes	1
species	Ethanol’s species checked

Choose vibe-qc (script), check the settings and selected species, then choose Write inputs. Preparing the script does not require a running queue.

Write and inspect the input

Click Write inputs. With this single species selected, the browser downloads one Python file. Its name is usually m1_b3lyp_def2-svp.py; the species id can differ in a document that has been edited.

Open the file in a text editor. It imports Atom, Molecule and run_job from vibeqc. Its calculation call should contain:

run_job(
    molecule,
    method="rks",
    functional="b3lyp",
    basis="def2-svp",
    output="m1_b3lyp_def2-svp",
    output_qvf=True,
    write_molden_file=True,
)

The Molecule has charge=0 and multiplicity=1. Its GEOMETRY list has nine atoms with coordinates in angstrom; the script converts them to bohr for vibe-qc. Coordinate values may differ between geometry-generation versions; the molecular identity and atom count should agree. Save the sketch again to retain its 3D structure.

The downloadable CLI and Python examples produce the same vibe-qc script with the same method, basis and task. The processes field sets the CPU request when submitting through vibe-queue.

Run a calculation when ready

Writing an input has not run or submitted a calculation. To run it directly, use the Python interpreter from your working vibe-qc installation:

/path/to/vibe-qc/.venv/bin/python m1_b3lyp_def2-svp.py

Replace the interpreter path and input filename with your actual files. For queued work, first configure vibe-queue and register vibeqc as described in Inputs. Submit to vibe-queue then prepares and submits the selected job, and Calculations reports its state.

Choose only settings that the vibe-qc writer supports. The writer reports unsupported requests instead of dropping options.

The reaction-to-publication tutorial continues through configuring a local queue, submitting to vibe-qc, following the runs and retrieving the calculation outputs with vq.

Calculation-result QVF files can be reopened to recover their structures. When editing a result, use Save As to a different file: the sketcher does not retain every calculation payload. Use vibe-view for detailed result inspection.

Optional: write an ORCA input

If your workflow also uses ORCA, change program to ORCA. Keep the method, basis and other settings above, and set MB each to 2000. Write inputs then downloads an .inp file containing ! B3LYP def2-SVP TightSCF, %maxcore 2000, %pal nprocs 1 end, and a geometry block beginning * xyz 0 1. Running that file requires a separate ORCA installation. See the ORCA writer reference for its supported options.