[Pw_forum] QE output about stress and pressure

[quantum]

Dear QE Friends:

I am working on the high-pressure mechanical characteristics of crystals.

At the end of a scf computation, the following lines are in the output file,

------------------------------------------------------------------------------------
     entering subroutine stress ...

          total   stress  (Ry/bohr**3)                   (kbar)     P=  241.85
   0.00051810  -0.00000000  -0.00008740         76.22     -0.00    -12.86
  -0.00000000   0.00304364   0.00000000         -0.00    447.74      0.00
  -0.00008740   0.00000000   0.00137038        -12.86      0.00    201.59
------------------------------------------------------------------------------------

Two questions:

(1) What is the meaning of "P=  241.85"?
(2) Could you please point me to the proper references to understand the meanings
    of the above output lines?

Thank you in advance.

Sincerely,
Tsung-Lung Li


Tsung-Lung Li, Ph. D.
Professor
Department of Applied Physics
National Chia-Yi University
300 Hsueh-Fu Road, Chiayi 60004, Taiwan
Phone: 886-5-2717904.  FAX: 886-5-2717909.
E-mail:quantum at mail.ncyu.edu.tw    
URL:http://web.ncyu.edu.tw/~quantum