Quickstart#
This quickstart is a high-level introduction on how to get started with using PYSEQM.
For full examples, please check out the examples directory in our GitHub repository.
1. Install PYSEQM#
Refer to Installation instructions.
2. Write Your First Input File#
Create a file called run_quickstart.py with the following contents:
#!/usr/bin/env python
import torch
from seqm.seqm_functions.constants import Constants
from seqm.Molecule import Molecule
from seqm.ElectronicStructure import Electronic_Structure
# 1. Precision & device
torch.set_default_dtype(torch.float64)
device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')
# 2. Define a simple molecule (H₂O)
species = torch.as_tensor([[8, 1, 1]], dtype=torch.int64, device=device)
coordinates = torch.tensor(
[[[0.00, 0.00, 0.00],
[0.96, 0.00, 0.00],
[-0.24, 0.93, 0.00]]],
dtype=torch.float64, device=device
)
const = Constants().to(device)
# 3. Set up SCF parameters
seqm_parameters = {
'method': 'AM1',
'scf_eps': 1e-8,
'scf_converger': [0, 0.1],
}
molecule = Molecule(const, seqm_parameters, coordinates, species).to(device)
# 4. Run single‐point SCF
driver = Electronic_Structure(seqm_parameters).to(device)
driver(molecule)
# 5. Print results
print(f"Total Energy (eV): {molecule.Etot.item():.6f}")
print(f"Heat of Formation: {molecule.Hf.item():.6f}")
print(f"Force on Atoms:\n{molecule.force}")
3. Execute the Script#
Run your quickstart script:
python run_quickstart.py
You should see printed:
Total energy (eV)
Heat of formation (eV)
Forces on each atom (eV/Å)
Next Steps#
Consult Initialization for batching, GPU, and input formats
Explore Single-Point SCF Calculations for more SCF options
Try CIS & RPA Excited State Calculations to compute excited states
See Born–Oppenheimer Molecular Dynamics (BOMD) for running MD trajectories