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QMInterface

omecp::qm_interface

Trait QMInterface 

Source 
pub trait QMInterface {
    // Required methods
    fn write_input(
        &self,
        geom: &Geometry,
        header: &str,
        tail: &str,
        path: &Path,
    ) -> Result<(), QMError>;
    fn run_calculation(&self, input_path: &Path) -> Result<(), QMError>;
    fn read_output(
        &self,
        output_path: &Path,
        original_geometry: &Geometry,
        state: usize,
    ) -> Result<State, QMError>;
}
Expand description

Trait that defines the interface for all quantum chemistry programs.

This trait must be implemented by each QM program to provide a uniform interface for MECP calculations. It handles the complete lifecycle of a single-point calculation: input generation, execution, and output parsing.

Required Methods§

Source

fn write_input( &self, geom: &Geometry, header: &str, tail: &str, path: &Path, ) -> Result<(), QMError>

Writes a calculation input file for the quantum chemistry program.

§Arguments
  • geom - Molecular geometry with element types and coordinates
  • header - Program-specific header section (methods, basis sets, options)
  • tail - Additional keywords or sections specific to the calculation
  • path - Output path for the input file
§Returns

Returns Ok(()) on success, or a QMError if file writing fails.

Source

fn run_calculation(&self, input_path: &Path) -> Result<(), QMError>

Executes the quantum chemistry calculation.

Runs the external QM program with the input file and waits for completion. The program output is captured and checked for success status.

§Arguments
  • input_path - Path to the input file to execute
§Returns

Returns Ok(()) if the calculation succeeds, or a QMError if:

  • The program cannot be executed (not found, permissions)
  • The calculation fails (non-zero exit status)
  • Runtime errors occur during execution
Source

fn read_output( &self, output_path: &Path, original_geometry: &Geometry, state: usize, ) -> Result<State, QMError>

Parses the calculation output file to extract results.

Reads and parses the program output file to extract the electronic state properties needed for MECP optimization.

§Arguments
  • output_path - Path to the output/log file to parse
  • state - Electronic state index to extract (0 = ground state, >0 = excited state)
§Returns

Returns a Result containing:

  • Ok(State) - Successfully parsed state with energy, forces, and geometry
  • Err(QMError::Parse) - Failed to parse required data from output
  • Err(QMError::IO) - Cannot read output file
§State Selection

The state parameter selects which electronic state to extract:

  • state = 0: Ground state (S0 for singlet, S1 for triplet, etc.)
  • state = n: n-th excited state (for TD-DFT calculations)

Different programs interpret this differently:

  • Gaussian: State index for TD-DFT excited states
  • ORCA: State index for excited state calculations
  • Other programs: May ignore this parameter

Implementors§