Input & Output

MAPLE input files (.inp) follow a simple, human-readable format. This guide covers the complete input file structure, all available header commands, coordinate formats, and the output files produced by each job type.

Input File Structure

A MAPLE input file consists of two main sections, processed in order:

Header commands -- Lines beginning with # that define the calculation type, model, device, and global options.
Coordinates -- Atomic coordinates provided inline or referenced from an external file.

Here is an example input file showing both sections:

#model=ani2x
#opt(method=lbfgs)
#device=gpu0
#convergence=tight

O    0.000000    0.000000    0.117300
H    0.000000    0.757200   -0.469200
H    0.000000   -0.757200   -0.469200

Header Commands

All header commands start with the # symbol. They are parsed first to determine the task type and global settings.

Command	Description	Example
`#model`	Select the ML potential model	`#model=ani2x`
`#sp`	Run a single point energy calculation	`#sp`
`#opt`	Run a geometry optimization	`#opt(method=lbfgs)`
`#ts`	Run a transition state search	`#ts(method=prfo)`
`#freq`	Compute vibrational frequencies	`#freq`
`#irc`	Run an intrinsic reaction coordinate calculation	`#irc(method=gs)`
`#scan`	Perform a potential energy surface scan	`#scan(method=lbfgs)`
`#device`	Set the compute device	`#device=gpu0`
`#convergence`	Set convergence level for iterative tasks	`#convergence=tight`

Note

If no task command (#opt, #ts, etc.) is specified, MAPLE automatically performs a single-point energy calculation using default settings.

Task Parameters

Task commands accept optional parameters in parentheses. If no parameters are given, MAPLE uses sensible defaults:

# With explicit parameters
#opt(method=lbfgs)
#convergence=tight

# Using defaults (equivalent to #opt(method=lbfgs))
#opt

Supported Models

MAPLE supports the following machine learning potential models, specified via the #model header command:

ani2x
ani1x
ani1ccx
ani1xnr
maceoff23s
maceoff23m
maceoff23l
egret
aimnet2
uma
maceomol
aimnet2nse

Convergence Levels

MAPLE provides six predefined convergence levels for iterative tasks such as geometry optimizations and transition state searches. Set the level using the #convergence header command:

#convergence=tight

The available levels, from tightest to loosest, are:

extratight
tight
medium (default)
loose
extraloose
superloose

See the Settings page for the exact numerical thresholds of each level.

Coordinate Formats

MAPLE supports two ways to specify molecular coordinates.

Inline Coordinates

The most common method. Specify atom symbol and Cartesian coordinates (in Angstroms) directly in the input file, one atom per line:

#model=ani2x

C    0.000000    0.000000    0.000000
H    0.629118    0.629118    0.629118
H   -0.629118   -0.629118    0.629118
H   -0.629118    0.629118   -0.629118
H    0.629118   -0.629118   -0.629118

External XYZ File

Reference an external .xyz file containing the coordinates. The XYZ file follows the standard format (atom count on line 1, comment on line 2, coordinates from line 3):

#model=ani2x
#opt

XYZ methane.xyz

Where methane.xyz contains:

5
Methane molecule
C    0.000000    0.000000    0.000000
H    0.629118    0.629118    0.629118
H   -0.629118   -0.629118    0.629118
H   -0.629118    0.629118   -0.629118
H    0.629118   -0.629118   -0.629118

Dual XYZ for NEB

For methods that require two endpoint structures (e.g., NEB), provide two XYZ references for the reactant and product geometries:

#model=ani2x
#ts(method=neb)

XYZ reactant.xyz
XYZ product.xyz

Output Files

MAPLE generates output files whose names and contents depend on the job type. The following table summarizes the primary output files:

Job Type	Output File	Contents
Single Point	`*.out`	Electronic energy (Eh)
Optimization	`*_opt.xyz`	Optimized geometry in XYZ format
Optimization	`*_opt_traj.xyz`	Full optimization trajectory
Frequency	`*_freq.out`	Vibrational frequencies, IR intensities, thermochemistry
Transition State	`*_ts.xyz`	Transition state geometry
IRC	`*_irc_forward.xyz`	Forward IRC path geometries
IRC	`*_irc_reverse.xyz`	Reverse IRC path geometries
PES Scan	`*_scan.xyz`	Geometries along the scan coordinate
PES Scan	`*_scan.dat`	Energy vs. scan coordinate data

In the table above, * represents the input file name (without the .inp extension). For example, running maple water_opt.inp with an optimization task produces water_opt_opt.xyz and water_opt_opt_traj.xyz.

Important

All energies are reported in Hartree (Eh) and all coordinates in Angstroms. Energy differences in iterative output are shown in kcal/mol for convenience.