**queation about DIIS ,H matrix.** |
- Date: 2007/09/21 20:21
- Name:
**Liger Chen**
<b89202066@ntu.edu.tw>
Hi :
The Newton method for structure opimize, be : x_new = x_old + H^(-1)*g Where x_new be the new atomic potitions waiting been calculated, x_old be the last output potitions, H be the Hessian, and g be the moving distance.
the well known DIIS algorithm , which introducts the alpha for acceleration of convergence and discuss last m steps :
x_new = x_old_m + (alpha)*g .
Obviously, The algorithm nelgects the H^(-1) term. So in some case the DIIS could not reach structure optimizing criterion. But in vasp , The DIIS performs so well. May I ask why ? thank you Liger
| |