The CP2K project : input section CELL_OPT

Section CELL_OPT

Index of all sections. This section is located at __ROOT__%MOTION%CELL_OPT.

This section sets the environment for the optimization of the simulation cell. Two possible schemes are available: (1) Zero temperature optimization; (2) Finite temperature optimization. This section can not be repeated and can be optional.

Subsections

Section keywords

Keyword descriptions

OPTIMIZER
OPTIMIZER {BFGS|LBFGS|CG}
Specify which method to use to perform a geometry optimization.
This optional keyword expects a keyword. Default value: BFGS
valid keywords:
  • BFGS: Most efficient minimizer, but only for 'small' systems, as it relies on diagonalization of a full Hessian matrix
  • LBFGS: Limit memory variant of the above, can also be applied to large systems, not as well fine-tuned
  • CG: conjugate gradients, robust minimizer (depending on the line search) also OK for large systems
variants: MINIMIZER
This keyword cites following reference: [BYRD1995]
MAX_ITER
MAX_ITER {integer}
Specifies the maximum number of geometry optimization steps. One step might imply several force evaluations for the CG and LBFGS optimizers.
This optional keyword expects an integer. Default value: 200
MAX_DR
MAX_DR {real}
Convergence criterium for the maximum geometry change between the current and the last optimizer iteration.
This optional keyword expects a real. Default unit: [bohr], default value: 3.0000000000000001E-03 bohr
MAX_FORCE
MAX_FORCE {real}
Convergence criterium for the maximum force component of the current configuration.
This optional keyword expects a real. Default unit: [bohr^-1hartree], default value: 4.4999999999999999E-04 bohr^-1hartree
RMS_DR
RMS_DR {real}
Convergence criterium for the root mean square (RMS) geometry change between the current and the last optimizer iteration.
This optional keyword expects a real. Default unit: [bohr], default value: 1.5000000000000000E-03 bohr
RMS_FORCE
RMS_FORCE {real}
Convergence criterium for the root mean square (RMS) force of the current configuration.
This optional keyword expects a real. Default unit: [bohr^-1hartree], default value: 2.9999999999999997E-04 bohr^-1hartree
STEP_START_VAL
step_start_val
The starting step value for the CELL_OPT module.
This optional keyword expects an integer. Default value: 0
TYPE
TYPE (GEO_OPT|MD)
Specify which kind of method to use for the optimization of the simulation cell
This optional keyword expects a keyword. Default value: GEO_OPT
valid keywords:
  • GEO_OPT: Performs a geometry optimization (the GEO_OPT section must be defined) between cell optimization steps. The stress tensor is computed at the optimized geometry.
  • MD: Performs a molecular dynamics run (the MD section needs must defined) for computing the stress tensor used for the cell optimization.
EXTERNAL_PRESSURE
EXTERNAL_PRESSURE {REAL} .. {REAL}
Specifies the external pressure (1 value or the full 9 components of the pressure tensor) applied during the cell optimization.
This optional keyword expects a list of reals. Default unit: [bar], default value: 1.0000000000000000E+02 0.0000000000000000E+00 0.0000000000000000E+00 0.0000000000000000E+00 \ 1.0000000000000000E+02 0.0000000000000000E+00 0.0000000000000000E+00 0.0000000000000000E+00 1.0000000000000000E+02 bar
KEEP_ANGLES
KEEP_ANGLES TRUE
Keep angles between the cell vectors constant, but allow the lenghts of the cell vectors to change independently. For example, a cubic cell might become orthorhombic, but not triclinic.
This optional keyword expects a logical
This keyword behaves as a switch T . Default value: F
PRESSURE_TOLERANCE
PRESSURE_TOLERANCE {REAL}
Specifies the Pressure tolerance (compared to the external pressure) to achieve during the cell optimization.
This optional keyword expects a real. Default unit: [bar], default value: 1.0000000000000000E+02 bar


Back to the CP2K homepage or the latest version of this manual