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[neb]

The [neb] section defines the product endpoint and image count for nudged elastic band calculations. Use it with [input] runtype=neb. All native NEB algorithm controls live in [oqp]; concise .oqp input routes them there automatically.

Keywords

product

Field Value
Type string
Default empty
Used by NEB product endpoint

Path to the product endpoint XYZ file. The reactant geometry comes from [input] system; the product geometry comes from product.

Example:

[neb]
product=HCN_RHF-DFT_NEB_OQP_product.xyz
nimage=7

nimage

Field Value
Type integer
Default 5
Used by NEB image count

Number of NEB images. The input checker requires at least 3.

For concise input, write the endpoint and native controls together:

dft/pbe0/def2-svp
neb(S0,product="product.xyz",images=7,spring=0.05,climb=true,output="path.xyz")
geom="reactant.xyz"

The concise images spelling lowers to nimage, and output lowers to [oqp] neb_output.

The remaining six keys are retained only for traditional .inp geomeTRIC NEB compatibility. Concise .oqp rejects them and uses native spring, fmax, frms, boolean climb, align, and opt_ends instead. The native replacements have different semantics or units, so old values should not be copied mechanically.

k

Field Value
Type float
Default 1.0
Used by legacy geomeTRIC NEB spring strength

maxg

Field Value
Type float
Default 0.1
Used by legacy geomeTRIC NEB maximum-gradient convergence

avgg

Field Value
Type float
Default 0.05
Used by legacy geomeTRIC NEB average-gradient convergence

climb

Field Value
Type float
Default 0.5
Used by legacy geomeTRIC NEB climbing threshold

This float is distinct from the boolean [oqp] climb used by native NEB.

align

Field Value
Type boolean
Default True
Used by legacy geomeTRIC NEB image alignment

optep

Field Value
Type boolean
Default False
Used by legacy geomeTRIC NEB endpoint optimization