# BFGS

Provides parameters to tune the BFGS optimization [Edit on GitHub]

Subsections

- RESTART

## Keywords

- RESTART_FILE_NAME

- RESTART_HESSIAN

- TRUST_RADIUS

- USE_MODEL_HESSIAN

- USE_RAT_FUN_OPT

## Keyword descriptions

RESTART_FILE_NAME: string

  Usage: RESTART_FILE_NAME {filename}

  Specifies the name of the file used to read the initial Hessian. [Edit on GitHub]

RESTART_HESSIAN: logical = F

  Lone keyword: `T`

  Usage: RESTART_HESSIAN

  Controls the reading of the initial Hessian from file. [Edit on GitHub]

TRUST_RADIUS: real = 2.50000000E-001 [angstrom]

  Usage: TRUST_RADIUS {real}

  Trust radius used in BFGS. Previously set to 0.1. Large values can lead to instabilities [Edit on GitHub]

USE_MODEL_HESSIAN: logical = F

  Lone keyword: `T`

  Usage: USE_MODEL_HESSIAN

  Uses a model Hessian as initial guess instead of a unit matrix. Should lead in general to improved convergence might be switched off for exotic cases [Edit on GitHub]

USE_RAT_FUN_OPT: logical = F

  Lone keyword: `T`

  Usage: USE_RAT_FUN_OPT

  Includes a rational function optimization to determine the step. Previously default but did not improve convergence in many cases [Edit on GitHub]