genice3

O que genice3 faz?

GenIce3 builds ice and clathrate hydrate structures whose hydrogen-bond network obeys the ice rules and whose net polarization is driven to a target (zero by default). This skill was written for GenIce3 3.0b7. If genice3 --version reports another version, trust the program's own --help, --list, and NAME? output over this file.

1. Make sure genice3 runs

Check with genice3 --version. If the command is missing, install it. When it is unclear which Python environment the user works in, ask before installing.

• Into the active virtual environment: pip install genice3
• Without installing anything: prefix every command with uvx, e.g. uvx genice3 1h
• As a standalone command: pipx install genice3

Python 3.11 or later is required. Do not install into a system or Homebrew Python; pip refuses with externally-managed-environment.

2. Look names up; never guess them

genice3 --list unitcell 2>&1    # ice phases, clathrates, zeolite frameworks
genice3 --list exporter 2>&1    # output formats
genice3 --list molecule 2>&1    # water models and guest molecules
genice3 'zeolite?'              # suboptions of one plugin (quote the ?)
genice3 CS2 -e cage_survey      # cage list as JSON; specs.cage_type is the label -g expects

--list writes to stderr. Names are case-sensitive (A15, not a15). An unknown name fails with a message listing the closest matches; use it to correct the command.

3. Build the command

genice3 UNITCELL [unit-cell options] [options] -e "EXPORTER :key value" > OUTPUT

• Coordinates go to stdout and the log to stderr, so always redirect stdout to a file.
• Always pass --seed N; otherwise each run gives a different proton arrangement.
• Supercell: --rep 2 2 2 (or --replication_matrix with 9 integers).
• Unit-cell options follow the unit-cell name: genice3 zeolite --code LTA, genice3 6 --density 1.00.
• The water model is an exporter suboption, not a top-level flag: -e "gromacs :water_model tip4p".
• Clathrate guests: run -e cage_survey first and read the cage_type labels. Then fill cages by type with -g A16=uathf (mixtures: -g "A12=co2*0.6+me*0.4") or a single cage by index with -G 0=me.
• Ions: -a/-c INDEX=ION put ions on unit-cell sites (repeated in every replica); -A/-C INDEX=ION replace one water molecule of the supercell. The numbers of cations and anions must be equal, otherwise the program may not terminate.
• Many settings: write a YAML file and run genice3 -Y config.yaml; command-line options override it. See reference/cli.md.

Typical commands:

genice3 1h --rep 4 4 4 --seed 1 -e "gromacs :water_model tip4p" > ice1h.gro
genice3 CS1 --rep 2 2 2 --seed 1 -g A12=me -g A14=me -e "gromacs :water_model tip4p" > cs1.gro
genice3 CS2 --seed 1 -g A16=uathf -G 0=me -e lammps > cs2.lammps
genice3 1h --rep 4 4 4 --seed 1 --pol_loop_2 10000 --target_polarization 0 0 40 > polarized.gro

4. Use the Python API when the CLI cannot do it

• H3O+ / OH- (add_spot_hydronium, add_spot_hydroxide) and Bjerrum L/D defects (add_bjerrum_L, add_bjerrum_D) exist only in the API. See reference/api/topological_defects.md.
• Also prefer the API to place things by coordinate, to write one structure in several formats, or to read the hydrogen-bond graph and molecular orientations.

import numpy as np
from genice3.genice import GenIce3
from genice3.plugin import Exporter

genice = GenIce3(replication_matrix=np.diag([2, 2, 2]), seed=42)
genice.set_unitcell("1h")   # unit-cell options as keywords: set_unitcell("zeolite", code="LTA")
with open("ice.gro", "w") as f:
    Exporter("gromacs").dump(genice, file=f, water_model="tip4p")

5. Check the result and report it

• On a nonzero exit status, read the ERROR: line on stderr; it says what to change.
• Confirm the output file is not empty. In a .gro file the second line is the number of atoms.
• Tell the user which seed was used, and that the structure obeys the ice rules but is not energy-minimized: it must be relaxed with the intended force field before a production run.
• If the structure will be used in a publication, point the user to reference/citation.md.

Reference files

Read only the file the task needs.

File	Read it for
reference/overview.md	Concepts, entry points, and common error messages with remedies
reference/cli.md	Every CLI option and the YAML configuration file
reference/basics.md	Replication, density, seeds, and polarization
reference/unitcells.md	Catalogue of unit cells and their suboptions
reference/clathrate-hydrates.md	Cage types, mixed occupancy, cage_survey
reference/guest-molecules.md	Built-in guest molecules
reference/water-models.md	Built-in water models
reference/output-formats.md	Exporters and their suboptions
reference/doping-and-defects.md	Unit-cell ions, spot ions, and defects
reference/plugins.md	Writing a new unit cell, molecule, or exporter plugin
reference/citation.md	How to cite GenIce
reference/api/*.md	Python API examples: basic, polarization, guest_occupancy, doping, topological_defects, cif_io, unitcell_transform, exotic_ice

The full manual is at https://genice-dev.github.io/GenIce3.