airsspy.fullrelax

Self-consistent CASTEP relaxation driver.

Replicates the behaviour of castep_relax.pl, performing iterative fixed-NPW geometry optimisations with restart capability and optional alternating cell constraints.

Module Contents

Classes

FullRelax

Self-consistent CASTEP relaxation with restart and state tracking.

Functions

check_relax_status	Check whether the last geometry optimisation completed.
parse_geom_text_output	Parse a CASTEP .geom file and return trajectory data.
geom_to_cell	Convert the last configuration in a .geom file to cell blocks.

Data

logger

API

airsspy.fullrelax.logger

‘getLogger(…)’

class airsspy.fullrelax.FullRelax(exe: str, struct_name: str, maxit: int, initial_cycle: int = 4, initial_length: int = 4, alter_cell_cons: bool = False)

Self-consistent CASTEP relaxation with restart and state tracking.

Performs iterative fixed-NPW geometry optimisations. Initial cycles use a short iteration count, then full-length cycles until two consecutive successful runs confirm convergence.

Initialization

Initialise a FullRelax instance.

Args: exe: CASTEP executable name/path. struct_name: Name of the structure to relax (without extension). maxit: Maximum geometry iterations (0 for single-point). initial_cycle: Number of initial short cycles. initial_length: Number of iterations in initial short cycles. alter_cell_cons: Alternate cell constraints on/off between cycles.

property dot_castep: str

property dot_param: str

property dot_cell: str

property dot_cell_out: str

check_param() → None

Ensure write_cell_structure is set in the PARAM file.

save_state() → None

Save the relaxation state to a JSON file.

load_state() → None

Load state from an unfinished run if present.

fixed_cell_off() → None

Remove fixed cell constraints and uncomment CELL_CONSTRAINTS block.

fixed_cell_on() → None

Comment out CELL_CONSTRAINTS block and add FIX_ALL_CELL.

run(timeout: Optional[float] = None) → str

Run the full relaxation procedure.

Args: timeout: Walltime limit in seconds.

Returns: "success" if converged, "limit reached" if maxit exceeded.

__repr__() → str

airsspy.fullrelax.check_relax_status(dot_castep: str) → tuple[bool, int]

Check whether the last geometry optimisation completed.

Args: dot_castep: Path to the .castep file.

Returns: Tuple of (relaxation_succeeded, total_iterations).

airsspy.fullrelax.parse_geom_text_output(out_lines: list[str]) → dict[str, numpy.ndarray]

Parse a CASTEP .geom file and return trajectory data.

Args: out_lines: Lines from the .geom file.

Returns: Dictionary with keys cells, positions, forces, geom_energy, symbols, and optionally velocities. All arrays are in CASTEP atomic units, converted to Angstrom/eV.

airsspy.fullrelax.geom_to_cell(geom_file: str) → tuple[str, str]

Convert the last configuration in a .geom file to cell blocks.

Args: geom_file: Path to the .geom file.

Returns: Tuple of (cell_block_string, position_block_string) including %BLOCK/%ENDBLOCK enclosures.