DAMP NEWTON

DAMP_NEWTON = real number 

Default: DAMP_NEWTON

= 0.8

{{{3}}}

Description: Sets the damping factor applied to the RPA forces during Newton-step structure relaxation.

---

DAMP_NEWTON controls the step size of the Newton-step geometry update performed during Random Phase Approximation (RPA) force calculations. The updated atomic positions are computed as:

x_new = x_current + DAMP_NEWTON × H⁻¹ · F_RPA

where H⁻¹ is the inverse of the DFT Hessian (computed during the RPA force calculation) and F_RPA are the RPA forces. The resulting updated positions are written to the CONTCAR file (provided NSW=0). Iterating this procedure—by copying CONTCAR to POSCAR and re-running—should converge the system toward its ground-state structure.

Mind: Available as of VASP 6.1.0

Available options

DAMP_NEWTON=1.0: No damping

No damping is applied; the full Newton step is taken. This is appropriate when the RPA forces

are well-behaved and the optimization is proceeding stably.

DAMP_NEWTON=0.8: Default damping

The default value. A mild damping factor of 0.8 is applied to the Newton step, providing a

small degree of stabilization during the iterative relaxation without significantly slowing convergence.

DAMP_NEWTON<0.8: Strong damping

Use smaller values if numerical instabilities are observed during the RPA relaxation.

Warning: Excessively small values will slow convergence considerably. Reduce DAMP_NEWTON only when large or erratic RPA forces are encountered.

Related tags and articles

CONTCAR, POSCAR, NSW, IBRION Workflows that use RPA force relaxation