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[pcm]

The [pcm] section controls implicit-solvent settings. The current production path is an energy-only reference-SCF PCM/ddX workflow for RHF/ROHF references.

Background

PCM replaces explicit solvent molecules with a dielectric continuum surrounding the solute cavity. In OpenQP, the production path uses ddX for domain-decomposition continuum models and currently couples that reaction field to the reference SCF energy. This page documents the implemented input contract; state-specific excited-state PCM, PCM gradients, and PCM optimizations are future workflow extensions. See References for PCM and domain-decomposition ddPCM literature.

Minimal Example

[pcm]
enabled=true
backend=ddx
mode=reference_scf
model=ddpcm
epsilon=78.3553

Python style:

from oqp.openqp import OpenQP

job = OpenQP("pcm_keywords")
job.molecule(geometry="water", charge=0, multiplicity=1)
job.theory.hf(basis="6-31g*")
job.workflow.pcm(
    enabled=True,
    backend="ddx",
    mode="reference_scf",
    model="ddpcm",
    epsilon=78.3553,
)

Keywords

enabled

Field Value
Type boolean
Default False
Used by PCM runtime activation

Enables the PCM reaction-field contribution. When true, the input checker requires the current production scope: backend=ddx, mode=reference_scf, runtype=energy, and RHF/ROHF.

backend

Field Value
Type string
Default ddx
Values ddx, pcmsolver
Used by PCM backend selection

Selects the PCM backend. Only ddx has an implemented runtime energy path in the current production scope.

mode

Field Value
Type string
Default reference_scf
Values reference_scf, reference_scf_plus_post_state, post_state_correction
Used by PCM coupling mode

Selects the coupling mode. Only reference_scf is currently implemented.

model

Field Value
Type string
Default ddpcm
Values ddcosmo, ddpcm, ddlpb, iefpcm, cpcm
Used by continuum model

Selects the continuum model. With backend=ddx, use ddcosmo, ddpcm, or ddlpb.

solvent

Field Value
Type string
Default water
Used by solvent label

Solvent label for readability and future solvent-model support.

epsilon

Field Value
Type float
Default 78.3553
Used by dielectric constant

Static dielectric constant. Must be numeric and greater than 1.

radii

Field Value
Type string
Default uff
Used by cavity radii model

Selects the cavity radii model.