Worked Example

Initial Imports

import multiprocessing
from scm.plams import JobRunner, config, Settings, read_molecules, AMSJob, init

# this line is not required in AMS2025+
init()

PLAMS working folder: /path/plams/examples/ManyJobsInParallel/plams_workdir

Configure Job Runner

Set the default job runner to run in parallel. Run as many jobs simultaneously as there are cpu on the system. In addition, set the number of cores for each job to 1.

maxjobs = multiprocessing.cpu_count()
print("Running up to {} jobs in parallel simultaneously".format(maxjobs))

Running up to 12 jobs in parallel simultaneously

config.default_jobrunner = JobRunner(parallel=True, maxjobs=maxjobs)

config.job.runscript.nproc = 1

Load Molecules

Load set of molecules from directory containing xyz files.

molecules = read_molecules("molecules")

Set Up and Run Jobs

Configure the calculation settings in the Settings object. Run a geometry optimization job for each molecule in parallel.

settings = Settings()
settings.input.ams.Task = "GeometryOptimization"
settings.input.dftb.Model = "GFN1-xTB"

results = []
for name, molecule in sorted(molecules.items()):
    job = AMSJob(molecule=molecule, settings=settings, name=name)
    results.append(job.run())

[10.02|15:50:35] JOB Acetic_acid STARTED
[10.02|15:50:35] JOB Benzene STARTED
[10.02|15:50:35] JOB Butane STARTED
[10.02|15:50:35] JOB Ethane STARTED
[10.02|15:50:35] JOB Ethanol STARTED
[10.02|15:50:35] JOB Butane RUNNING
[10.02|15:50:35] JOB Formic_acid STARTED
[10.02|15:50:35] JOB Acetic_acid RUNNING
[10.02|15:50:35] JOB Methanol STARTED
[10.02|15:50:35] JOB Water STARTED

Results

Print a table of results only for the successful calculations.

# Only print the results of the successful calculations:
for result in [r for r in results if r.ok()]:
    print("Energy for {:<12}: {:>10.3f} kcal/mol".format(result.name, result.get_energy(unit="kcal/mol")))

[10.02|15:50:35] Waiting for job Acetic_acid to finish
[10.02|15:50:35] JOB Formic_acid RUNNING
[10.02|15:50:35] JOB Benzene RUNNING
[10.02|15:50:35] JOB Water RUNNING
[10.02|15:50:35] JOB Ethane RUNNING
[10.02|15:50:35] JOB Ethanol RUNNING
[10.02|15:50:35] JOB Methanol RUNNING
[10.02|15:50:36] JOB Water FINISHED
[10.02|15:50:36] JOB Formic_acid FINISHED
[10.02|15:50:36] JOB Butane FINISHED
[10.02|15:50:36] JOB Acetic_acid FINISHED
... (PLAMS log lines truncated) ...
[10.02|15:50:36] Waiting for job Benzene to finish
[10.02|15:50:37] Waiting for job Ethanol to finish
Energy for Acetic_acid :  -9913.297 kcal/mol
Energy for Benzene     : -12039.482 kcal/mol
Energy for Butane      :  -8699.182 kcal/mol
Energy for Ethane      :  -4686.354 kcal/mol
Energy for Ethanol     :  -7629.287 kcal/mol
Energy for Formic_acid :  -7890.662 kcal/mol
Energy for Methanol    :  -5621.724 kcal/mol
Energy for Water       :  -3618.401 kcal/mol