MSRRHO Thermochemistry

MSRRHO evaluates finite-temperature thermochemistry from a molecular structure and vibrational levels. It is designed as a fast backend-side calculation: no worker pod is launched, but the SDK interface remains job-like for consistency (submit, wait, result, require_result).

Your First MSRRHO Job

import atomiverse
from atomiverse import Atoms, JobFailedError, MSRRHO

atomiverse.configure(api_key="your-api-key")

water = Atoms.from_smiles("O")

job = MSRRHO(
    atoms=water,
    vibrational_levels_cm1=[1595.0, 3657.0, 3756.0],
    temperature_start=250.0,
    temperature_stop=350.0,
    temperature_step=50.0,
)

job.submit(wait=True)

try:
    result = job.require_result()
except JobFailedError as exc:
    print(f"MSRRHO failed: {exc.failure.error}")
else:
    print(f"ZPE: {result.zpe_kj_per_mol:.3f} kJ/mol")
    print(f"Point group: {result.point_group}, symmetry: {result.symmetry_number}")
    for row in result.properties:
        print(
            f"T={row.temperature:6.1f} K "
            f"G={row.gibbs_energy_kj_per_mol:10.3f} kJ/mol "
            f"S={row.entropy_total_j_per_mol_k:10.3f} J/(mol K)"
        )
    result.dump("msrrho-output")

Inputs

Field	Type	Units	Notes
atoms	Atoms	-	Non-periodic molecule geometry
vibrational_levels_cm1	list[float]	cm^-1	Harmonic levels; must be non-empty
temperature_start	float	K	Start of sampled grid
temperature_stop	float	K	End of sampled grid (inclusive)
temperature_step	float	K	Grid spacing (> 0)
pressure	float	Pa	Default 101325.0
multiplicity	int	-	Spin multiplicity, default 1
symmetry_number	int | None	-	Rotational symmetry number; guessed automatically when omitted
treat_internal_energy	bool	-	Include the internal-energy correction

Result

job.require_result() returns an MSRRHOResult with:

Field	Type	Units
zpe_kj_per_mol	float	kJ/mol
zpe_kcal_per_mol	float	kcal/mol
pressure	float	Pa
symmetry_number	int	-
point_group	str | None	-
properties	list[MSRRHOTemperatureProperties]	per-temperature rows

Each properties row includes:

Field	Units
temperature	K
internal_energy_kj_per_mol	kJ/mol
internal_energy_kcal_per_mol	kcal/mol
entropy_vibrational_j_per_mol_k	J/(mol K)
entropy_ideal_j_per_mol_k	J/(mol K)
entropy_electronic_j_per_mol_k	J/(mol K)
entropy_total_j_per_mol_k	J/(mol K)
helmholtz_energy_kj_per_mol	kJ/mol
helmholtz_energy_kcal_per_mol	kcal/mol
gibbs_energy_kj_per_mol	kJ/mol
gibbs_energy_kcal_per_mol	kcal/mol

Notes

• The temperature grid is sampled as start, start + step, ... and includes stop when the endpoint lands on the step grid.
• Negative vibrational values are accepted and treated by magnitude when converted for MSRRHO processing.
• The rotational symmetry number is guessed from the molecular geometry when symmetry_number is omitted.
• Use result.dump("folder") to write the per-temperature table to folder/msrrho.csv.
• MSRRHO currently runs only on managed backend compute. BYOC targets are rejected for this job type.