Module parser 

Input file parsing for OpenMECP configuration.

This module provides parsing functionality for OpenMECP input files, which use a custom section-based format. The parser handles:

• Geometries: Main geometry and LST interpolation geometries
• Configuration: All calculation parameters (method, program, etc.)
• Constraints: Bond lengths, angles, and fixed atoms
• Tail sections: Additional keywords for each state

Input File Format

OpenMECP input files use a section-based syntax marked with *SECTION markers and terminated with *. The format is designed to be human-readable and flexible for different types of calculations.

Required Sections

*GEOM Section

Contains the initial molecular geometry in Cartesian coordinates:

*GEOM
C  0.0  0.0  0.0
H  1.0  0.0  0.0
H  0.0  1.0  0.0
*

Can also reference external files:

*GEOM
@geometry.xyz
*

Key-Value Parameters

After sections, specify calculation parameters:

program = gaussian
method = B3LYP/6-31G*
nprocs = 4
mem = 4GB
charge = 0
mult_state_a = 1  # or mult_a = 1
mult_state_b = 3  # or mult_b = 3

Optional Sections

• *TAIL_a / *TAIL_b: Additional keywords for each electronic state
• *CONSTR: Geometric constraints (bonds, angles, scans)
• *LST_a / *LST_b: Geometries for linear synchronous transit interpolation

Examples

use omecp::parser::{parse_input, InputData};
use std::path::Path;

// Parse an input file
let input_path = Path::new("input.inp");
let input_data: InputData = parse_input(input_path)?;

// Access parsed data
let config = input_data.config;
let geometry = input_data.geometry;
let constraints = input_data.constraints;

Structs

InputData

Complete parsed input data from an OpenMECP input file.

Enums

ParseError

Error type for parsing operations.

Functions

constraints_are_equivalent 🔒

Checks if two constraints are equivalent (define the same geometric parameter).

create_user_friendly_tail_error 🔒

Creates a user-friendly error message for tail section validation failures.

filter_tail_content

Filters comments and cleans tail section content.

get_tail_section_suggestions 🔒

Provides suggestions for fixing common tail section formatting issues.

is_comment_line

Checks if a line is a comment line.

log_empty_tail_section_info 🔒

Logs informational message about empty tail sections after filtering.

parse_angle_target 🔒

Parses an angle target value (in degrees) with validation.

parse_atom_index 🔒

Parses an atom index from a string with detailed error reporting.

parse_bool 🔒

Parses a boolean value from a string, supporting multiple formats.

parse_constraint 🔒

Parses a single constraint line from the *CONSTR section.

parse_distance_target 🔒

Parses a distance target value with validation.

parse_input

Parse an OpenMECP input file.

parse_parameter

Parses configuration from a string content. All thresholds and coordinates use Angstrom-based units internally.

parse_scan 🔒

read_external_geometry 🔒

read_geom_from_gjf 🔒

read_geom_from_log 🔒

read_geom_from_xyz 🔒

validate_constraints_against_geometry 🔒

Validates parsed constraints against the molecular geometry.

validate_gaussian_keywords

Validates Gaussian keyword syntax.

validate_gaussian_syntax

Validates basic Gaussian syntax patterns.

validate_tail_section

Validates tail section content for Gaussian compatibility.

validate_tail_section_with_context

Validates tail section content with enhanced context and error reporting.

validate_tail_section_with_filtering_context

Validates tail section content with filtering context awareness.

Type Aliases

Result 🔒

Type alias for parse operation results