qclint

qclint is a Go command and reusable package for validating Gaussian and ORCA input files. Format adapters share the same chemistry and resource policy instead of duplicating those rules in the CLI.

Build and test

go test ./...
go build -o build/qclint ./cmd/qclint
make install PREFIX=/desired/prefix

The module requires Go 1.23 or newer and has no third-party dependencies.

Charge and multiplicity checker

qclint reads the charge, multiplicity, processor count, and memory declared by Gaussian .gjf/.com and ORCA .inp/.in/.orca inputs. It calculates the electron count from the molecular specification and checks both physical consistency and user resource limits.

Create the user configuration first:

qclint config init
qclint config show

The default path follows the platform user configuration convention (~/.config/qclint/config on Linux). Set QCLINT_CONFIG to use a different path. If the configuration is missing, normal checks stop with an error. The file contains an integer core limit and decimal memory limits:

max_cores = 32       # maximum CPU cores
gaussian_max_memory = 63.5GB # maximum Gaussian memory
orca_max_memory = 50.75GB    # maximum ORCA memory

Memory values may be integers or decimal GB values. They are converted to the nearest byte; scientific notation and ambiguous units such as GiB are not accepted.

Expected charge and multiplicity values are optional:

qclint molecule.gjf
qclint --charge 0 --multiplicity 3 molecule.gjf
qclint --multiplicity 2 inputs/*.inp

Fixes are selectable and composable:

qclint --fix chk molecule.gjf
qclint --fix cores --fix memory calculation.inp
qclint --fix-all inputs/*.inp
qclint --fix-all --dry-run inputs/*.inp

Charge and multiplicity are check-only fields. They are never modified by --fix or --fix-all.

ORCA support includes ! PALn, one-line and multiline %pal blocks, %maxcore, inline xyz/int/internal/gzmt coordinates, %coords blocks, and external xyzfile geometries. Since ORCA MaxCore is specified in MB per process, qclint checks total requested memory as MaxCore * nprocs. Gaussian and ORCA have independent absolute GB allocations, so users can account for each program's memory behavior without interpreting percentages. Requesting less memory produces an underallocation warning, an exact match is silent, and requesting more is an error. ORCA memory fixes derive the per-process MaxCore value from orca_max_memory and the effective process count. --fix memory sets either an underallocated or excessive request to the maximum usable configured allocation.

Processor allocation follows the same exclusive-node policy: fewer than max_cores produces a warning, an exact match is silent, and more is an error. --fix cores sets any non-matching processor request to max_cores.

Gaussian memory supports byte and word units (KB/MB/GB/TB and KW/MW/GW/TW), bare word counts, %NProcShared, and %CPU processor lists. Gaussian directives use its native unit spellings rather than KiB/MiB/GiB/TiB. ONIOM state lists, ghost centers, complete --Link1-- jobs, and checkpoint-geometry inheritance are recognized.

ORCA $new_job sections are checked independently. Compound scripts receive strict global PAL/MaxCore checks, but dynamically generated geometries are reported as not statically checkable rather than being guessed. Automatic fixes are deliberately limited to single-job documents; multi-job documents are fully checked but left unchanged when a fix cannot be proven safe.

Output

Successful checks are silent by default. Pass multiple files with shell wildcards; qclint does not scan directory arguments. Unsupported file extensions and directories are discarded before opening a file or loading the user configuration. Diagnostics use a compiler-style format and are written to standard error:

inputs/water.gjf:2: error[resource.cores]: requested 64 cores; maximum is 32
inputs/job.inp: warning[chem.unchecked]: generated geometry cannot be checked statically

Use -v or --verbose to list passed and skipped files and print a summary:

inputs/water.gjf: note[check.ok]: passed
notes.txt: note[input.skipped]: unsupported extension .txt
qclint: checked=1 passed=1 failed=0 skipped=1

Severity labels are colored only when standard error is an interactive terminal. Redirected output and CI logs remain plain text; setting NO_COLOR also disables color.

Exit codes

• 0: every supported input passed, no supported inputs were found, or a configuration command succeeded.
• 1: at least one input failed a lint check.
• 2: command-line, configuration, file access, or parsing error.

qclint --version prints the installed version. Run the native Go fuzz target with:

make fuzz

The reusable API is provided by github.com/wxia529/qclint/qclint. ParseGaussian, ParseORCA, CheckChargeMultiplicity, CheckResources, and FixFile can be used without the command-line front end.