Exploring the order parameter (explore task)

This example shows the explore task on the 1D double well. An exploratory run wanders the order-parameter space without enforcing interface conditions, so it is a convenient first step when you do not yet know a good order parameter or where to place the interfaces. The visited order-parameter range and the generated trajectories then guide interface placement for a subsequent TIS/RETIS run, and can be reused as initial paths (see Getting the initial path).

Verification status: smoke – see Example test status.

Tutorial quick start

• Best starting point: examples/tutorials/path_sampling/1D-double-well/explore/.
• Edit first: task = "explore" and the interfaces list in the [simulation] section; the order parameter in [orderparameter].
• Run: pyretisrun -i explore.toml -p from the tutorial folder.
• Expected output: per-ensemble folders (000, 001, …) with order.txt / energy.txt recording the explored order-parameter range; no crossing-probability analysis (an explore run is for scouting, not rate estimation).
• Related check: examples/tests/test-internal/explorer/; see Example test status.

Selecting the explore task

The explore task is requested in the simulation section; the rest of the input is structured like an ordinary TIS run (interfaces, engine, order parameter), and the initial configuration is provided through the usual initial-path section:

[simulation]
task = "explore"
steps = 2000
interfaces = [
    -0.9,
    -0.5,
    1.0,
]
seed = 0

Running the exploration

Show/hide the full input file »

potential = [
    { class = "DoubleWell", a = 1.0, b = 2.0, c = 0.0 },
]

[simulation]
task = "explore"
steps = 2000
interfaces = [
    -0.9,
    -0.5,
    1.0,
]
seed = 0

[system]
units = "reduced"
dimensions = 1
temperature = 0.07

[engine]
class = "Langevin"
timestep = 0.002
gamma = 0.3
high_friction = false
seed = 0

[box]
periodic = [
    false,
]

[particles]
name = [
    "Ar",
]
ptype = [
    0,
]

[particles.position]
input_file = "initial.xyz"

[particles.velocity]
generate = "maxwell"
momentum = false
seed = 0

[particles.mass]
Ar = 1.0

[forcefield]
description = "1D double well"

[orderparameter]
class = "Position"
dim = "x"
index = 0
periodic = false

[output]
energy-file = 100
order-file = 100
trajectory-file = 100

[tis]
freq = 0.5
maxlength = 2000
allowmaxlength = false
zero_momentum = false
rescale_energy = false
sigma_v = -1
seed = 0

[initial-path]
method = "kick"
kick-from = "initial"

The initial configuration initial.xyz ships in the tutorial folder. Run with:

pyretisrun -i explore.toml -p

Tested by

The explore task is represented by examples/tutorials/path_sampling/1D-double-well/explore/ (in the tutorial smoke suite) and checked numerically by examples/tests/test-internal/explorer/.