Parameters for calculating hessian
Parameters here are for calculating hessian matrix. The hessian matrix is defined as the square matrix of second-order partial derivatives of the total energy with respect to the displacement of atomic position. Note that the dynamical matrix can be obtained by including the mass-related coefficients.
calculation.hessian.movingAtoms
keyword: calculation.hessian.movingAtoms
possible values: integer array
default value: all atoms in the central cell for molecular or bulk system; no default value for system with probes
description: Within the whole hessian matrix, only those elements of the sub-matrix corresponding to the atoms listed in the movingAtoms will be calculated.
an example:
calculation.hessian.movingAtoms = [10:291]
calculation.hessian.delta
keyword: calculation.hessian.delta
possible values: a double number
default value: 0.03 au
description: A small displacement of atomic position used to calculate the hessian matrix by numerical derivatives of forces.
an example:
calculation.hessian.delta = 0.01
calculation.hessian.primitiveCellVectors
keyword: calculation.hessian.primitiveCellVectors
possible values: 3 x 3 double matrix
default value: same as that of the super cell
description: Hessian matrix is normally calculated with a large super cell (the current cell), and this parameter defines a smaller cell. The Hessian matrix being consistent with the smaller cell will be given after the calculation.
an example:
calculation.hessian.primitiveCellVectors = ...
[0 1 1; 1 0 1; 1 1 0]/2*5.408
calculation.hessian.order
keyword: calculation.hessian.order
possible values: 2, 3, or 5
default value: 3
description: The number of points used to calculate the derivative of force numerically.
an example:
calculation.hessian.order = 2
calculation.hessian.plot
keyword: calculation.hessian.plot
possible values: true or false
default value: false
description: If true, a plot will be given for checking the convergence of the Hessian matrix elements with the increase of the distance between atoms.
an example:
calculation.hessian.plot = true
calculation.hessian.vdwInteractionQ
keyword: calculation.hessian.vdwInteractionQ
possible values: true or false
default value: false
description: If true, van der Waals interaction will be included.
an example:
calculation.hessian.vdwInteractionQ = true
calculation.hessian.vdwInteractionParameter.method
keyword: calculation.hessian.vdwInteractionParameter.method
possible values: ‘Grimme’
default value: ‘Grimme’
description: The parameter vdwInteractionParameter is a structure with many fields. Here the field method gives the method for the van der Waals interaction calculation. For how to set other fields of the structure, please refer to the description of the parameter calculation.vdwForce.
an example:
calculation.hessian.vdwInteractionParameter = []
calculation.hessian.vdwInteractionQ
keyword: calculation.hessian.vdwInteractionQ
possible values: true or false
default value: false
description: If true, van der Waals interaction will be included.
an example:
calculation.hessian.vdwInteractionQ = true
calculation.hessian.vdwInteractionParameter.method
keyword: calculation.hessian.vdwInteractionParameter.method
possible values: ‘Grimme’
default value: ‘Grimme’
description: The parameter vdwInteractionParameter is a structure with many fields. Here the field method gives the method for the van der Waals interaction calculation. For how to set other fields of the structure, please refer to the description of the parameter calculation.vdwForce.
an example:
calculation.hessian.vdwInteractionParameter = []