Module checkpoint 

Restart functionality Checkpoint system for saving and restarting MECP calculations.

This module provides functionality to save the complete state of a MECP optimization calculation and restart from that state later. This is essential for:

• Long calculations: Save progress periodically
• Interrupted jobs: Restart from the last checkpoint
• Parameter testing: Resume with different settings
• Convergence recovery: Restart from near-converged geometries

Checkpoint Format

Checkpoints are stored as JSON files containing:

• Step number: Current optimization step
• Geometry: Current molecular geometry
• Optimization history: Geometries, gradients, Hessians (for DIIS)
• Hessian matrix: Current approximate Hessian
• Configuration: Complete calculation settings

Serialization Strategy

The checkpoint system uses serde for serialization. Since some types (DVector, DMatrix) from nalgebra don’t directly serialize, wrapper types are used:

• SerializableGeometry: Converts DVector coords to Vec<f64>
• SerializableOptimizationState: Converts collections of DVector/DMatrix to Vec

Usage

Checkpoints are automatically created during optimization but can also be used manually:

use omecp::checkpoint::{Checkpoint, CheckpointLoad};
use omecp::geometry::Geometry;
use omecp::optimizer::OptimizationState;
use omecp::config::Config;
use nalgebra::{DMatrix, DVector};
use std::path::Path;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Create test data
    let elements = vec!["H".to_string()];
    let coords = vec![0.0, 0.0, 0.0];
    let geometry = Geometry::new(elements, coords);
    let x_old = DVector::from_vec(vec![0.0, 0.0, 0.0]);
    let hessian = DMatrix::identity(3, 3);
    let opt_state = OptimizationState::new(5);
    let config = Config::default();

    // Save checkpoint
    let checkpoint = Checkpoint::new(1, &geometry, &x_old, &hessian, &opt_state, &config);
    checkpoint.save(Path::new("mecp.chk"))?;

    // Load checkpoint
    let loaded: CheckpointLoad = Checkpoint::load(Path::new("mecp.chk"))?;
    println!("Loaded step: {}", loaded.step);

    std::fs::remove_file("mecp.chk")?;
    Ok(())
}

File Location

Checkpoint files are typically saved as mecp.chk or a user-specified name in the running_dir/ directory for easy management. Checkpoint system for restarting MECP optimizations.

This module provides functionality to save and restore optimization state including geometry, gradients, Hessian, and history for recovery.

Structs

Checkpoint

Checkpoint structure for saving/restoring MECP calculations.

CheckpointLoad

Loaded checkpoint contents returned by Checkpoint::load.

SerializableGeometry

Serializable wrapper for Geometry.

SerializableOptimizationState

Serializable wrapper for OptimizationState.

Functions

default_version 🔒

Default checkpoint version for backward compatibility.