"""Defined interactions for improper-style connections."""
from typing import Optional, Tuple
import unyt as u
from pydantic import ConfigDict, Field
from gmso.core.parametric_potential import ParametricPotential
from gmso.utils.expression import PotentialExpression
[docs]
class ImproperType(ParametricPotential):
"""A description of the interaction between 4 bonded partners.
This is a subclass of the gmso.core.Potential superclass.
ImproperType represents a improper type and includes the functional form
describing its interactions. The functional form of the potential is stored
as a `sympy` expression and the parameters, with units, are stored
explicitly. The AtomTypes that are used to define the improper type are
stored as `member_types`.
The connectivity of an improper is:
m2
m3 - m1 - m4
where m1, m2, m3, and m4 are connection members 1-4, respectively.
Notes
----
Inherits many functions from gmso.ParametricPotential:
__eq__, _validate functions
"""
member_types_: Optional[Tuple[str, str, str, str]] = Field(
None,
description="List-like of gmso.AtomType.name "
"defining the members of this improper type",
alias="member_types",
)
member_classes_: Optional[Tuple[str, str, str, str]] = Field(
None,
description="List-like of gmso.AtomType.atomclass "
"defining the members of this improper type",
alias="member_classes",
)
model_config = ConfigDict(
alias_to_fields=dict(
**ParametricPotential.model_config["alias_to_fields"],
**{
"member_types": "member_types_",
"member_classes": "member_classes_",
},
),
)
def __init__(
self,
name="ImproperType",
expression=None,
parameters=None,
independent_variables=None,
potential_expression=None,
member_types=None,
member_classes=None,
tags=None,
):
super(ImproperType, self).__init__(
name=name,
expression=expression,
parameters=parameters,
independent_variables=independent_variables,
potential_expression=potential_expression,
member_types=member_types,
member_classes=member_classes,
tags=tags,
)
@property
def member_types(self):
"""Return member information for this ImproperType."""
return self.__dict__.get("member_types_")
@property
def member_classes(self):
return self.__dict__.get("member_classes_")
@staticmethod
def _default_potential_expr():
return PotentialExpression(
expression="0.5 * k * ((phi - phi_eq))**2",
parameters={
"k": 1000 * u.Unit("kJ / (deg**2)"),
"phi_eq": 180 * u.deg,
},
independent_variables={"phi"},
)