.. _user-guide-path-types-rejections: Path types and rejection reasons ================================= During a |pyretis| simulation, each Monte Carlo cycle generates (or loads) a path and records two short codes in the output: * a **move type** (how the path was generated), and * a **status code** (whether the path was accepted, and if not, why). Both codes appear in the per-ensemble output files and in the simulation log, e.g.:: # Cycle: 42, status: ACC, move: sh The tables below list every code that |pyretis| can produce. .. _user-guide-path-move-types: Move types ---------- The move type describes how the new path was generated. .. list-table:: :header-rows: 1 :widths: 10 30 60 * - Code - Short name - Description * - ``sh`` - Shoot - Path generated with a **shooting move**: a phase-space point is selected on the current path, momenta are perturbed, and new forward and backward trajectories are integrated. * - ``ss`` - Stone skipping - Path generated by the **Stone Skipping** algorithm, a multi-step variant of shooting that reuses short sub-paths. * - ``wt`` - Web Throwing - Path generated by the **Web Throwing** move. * - ``wf`` - Wire Fencing - Path generated by the **Wire Fencing** move. * - ``ts`` - Target swap - Path generated by a **target swap** move. * - ``tr`` - Time-reversal - Path generated by **time-reversal**: the current accepted path is reversed in time to produce the trial path. * - ``s+`` - Swap from + - Path produced by a **replica-swap** move where the incoming path came from the ``+`` (higher-index) ensemble. * - ``s-`` - Swap from − - Path produced by a **replica-swap** move where the incoming path came from the ``-`` (lower-index) ensemble. * - ``mr`` - Mirror - Path generated by a **mirror** move. * - ``ki`` - Kick initiation - Path generated by integrating the equations of motion after **kicking** (re-drawing) the initial momenta; used during path initiation. * - ``is`` - Initial shoot - Path generated by a **shooting move** applied during the initial Stone Skipping preparation step, before the actual SS move. * - ``ld`` - Load (unformatted) - Path **loaded from unformatted** (binary) external file(s). * - ``re`` - Load (formatted) - Path **loaded from formatted** (text) external file(s). * - ``00`` - Null move - Path produced by a **null move**: the current path is kept without any modification (used internally). .. _user-guide-path-status-codes: Path status codes ----------------- The status code explains why the trial path was accepted or, if rejected, what condition was violated. **Acceptance** .. list-table:: :header-rows: 1 :widths: 10 90 * - Code - Meaning * - ``ACC`` - The trial path was **accepted** and becomes the new current path. **Trajectory-length rejections** These rejections occur when the generated trajectory is too long or too short to satisfy the detailed-balance or max-length conditions. .. list-table:: :header-rows: 1 :widths: 10 90 * - Code - Meaning * - ``BTL`` - **Backward trajectory too long** — the backward segment exceeded the limit imposed by the detailed-balance condition. * - ``BTX`` - **Backward trajectory too long** — the backward segment exceeded the hard ``maxlength`` cut-off. * - ``BTS`` - **Backward trajectory too short** — the backward segment ended before reaching a required interface. * - ``FTL`` - **Forward trajectory too long** — the forward segment exceeded the limit imposed by the detailed-balance condition. * - ``FTX`` - **Forward trajectory too long** — the forward segment exceeded the hard ``maxlength`` cut-off. * - ``FTS`` - **Forward trajectory too short** — the forward segment ended before reaching a required interface. * - ``XSS`` - **Stone Skipping sub-path too long** — an internal sub-path within the Stone Skipping algorithm exceeded the allowed length. **Interface / crossing rejections** .. list-table:: :header-rows: 1 :widths: 10 90 * - Code - Meaning * - ``NCR`` - **No crossing with the middle interface** — the trial path did not cross the required central interface of the ensemble. * - ``BWI`` - **Backward trajectory ends at wrong interface** — the backward segment terminated at an interface other than the one required. * - ``EWI`` - **Initial path ends at wrong interface** — used during path loading/initiation: the loaded path ends at an interface that is not compatible with the ensemble. * - ``SWI`` - **Initial path starts at wrong interface** — used during path loading/initiation: the loaded path starts at an interface that is not compatible with the ensemble. * - ``0-L`` - **{0−} path ends at left interface** — for paths in the ``{0-}`` ensemble the path ended at the left (A-state) interface instead of crossing to the right. * - ``NSS`` - **No one-step crossing in Stone Skipping** — the Stone Skipping algorithm could not find a valid one-step interface crossing. **Momentum / energy rejections** .. list-table:: :header-rows: 1 :widths: 10 90 * - Code - Meaning * - ``MCR`` - **Momenta change rejection** — the new momenta drawn during the shooting move were rejected (e.g. by the Metropolis criterion on the kinetic energy). * - ``KOB`` - **Kicked outside of boundaries** — after the momentum kick the system moved outside the allowed phase-space boundaries. **Detailed-balance / super-detailed-balance rejections** These rejections enforce the (super) detailed-balance conditions for advanced moves. .. list-table:: :header-rows: 1 :widths: 10 90 * - Code - Meaning * - ``HAS`` - **High-acceptance swap rejection** — the high-acceptance criterion for Stone Skipping / Wire Fencing detailed balance was not satisfied. * - ``SSA`` - **Stone Skipping super-detailed-balance rejection** — the Stone Skipping move was rejected by the super-detailed-balance acceptance test. * - ``WFA`` - **Wire Fencing super-detailed-balance rejection** — the Wire Fencing move was rejected by the super-detailed-balance acceptance test. * - ``WTA`` - **Web Throwing super-detailed-balance rejection** — the Web Throwing move was rejected by the super-detailed-balance acceptance test. **Target-swap rejections** .. list-table:: :header-rows: 1 :widths: 10 90 * - Code - Meaning * - ``TSS`` - **Target swap selection rejection** — the target-swap move was rejected at the selection step (no suitable target ensemble was found). * - ``TSA`` - **Target swap detailed-balance rejection** — the target-swap trial was rejected by the detailed-balance acceptance criterion. **REPPTIS-specific rejections** .. list-table:: :header-rows: 1 :widths: 10 90 * - Code - Meaning * - ``SWD`` - **REPPTIS swap — wrong propagation direction** — in a REPPTIS swap move the trial trajectory propagated in the wrong direction relative to the interface. * - ``SWH`` - **REPPTIS swap — first-half extension rejected** — the first half of the REPPTIS swap extension was rejected. **Other** .. list-table:: :header-rows: 1 :widths: 10 90 * - Code - Meaning * - ``NSG`` - **No suitable segments** — the path contains no segments that can be used as shooting points. * - ``EXP`` - **Exploration path** — the path was generated during an exploration phase and is not counted as a regular MC step.