[Pw_forum] how to set nr1b, nr2b, nr3b for cp.x when using ultrasoft pseudopotential

vega lew quantumdft at gmail.com
Wed Nov 18 06:17:53 CET 2009

Dear all,

I used to submit an manuscript to a specialized journal about chemistry and
physics. The referees suggested me to perform some molecular dynamics. I now
agree with the referees that the molecular dynamics is essential to confirm
the configurations from pw.x. But I have little experience in First
principle molecular dynamic, but I have a good impression of classical MD.
So I think I could accomplish it with some learning from more experienced
people. Following the excellent manual provided by the website, I try to use
cp.x code to perform molecular dynamics on my systems. Now it is running...

But I have a question about the option "nr1b, nr2b, nr3b" in &SYSTEM
namelist. Could you please tell me something more about it?
How to determine the proper value for different systems. Do you think it
could greatly increase the computational time consumption if the value is
not properly set?
I want to calculate a system of 147 atoms with 48 [TiO2] units and a water
molecule. And following the autopilot example, I set these three value to 20
repectively. do you think it is reasonable for this system?
If not, could you please tell me something about how to set it properly.

thank you for reading.

any suggestion is deeply appreciated. Thank you in advance.

best wishes,


Vega Lew ( weijia liu)
Graduate student
State Key Laboratory of Materials-oriented Chemical Engineering
College of Chemistry and Chemical Engineering
Nanjing University of Technology, 210009, Nanjing, Jiangsu, China
Email: vegalew at gmail.com
Office: Room A705, Technical Innovation Building, Xinmofan Road 5#, Nanjing,
Jiangsu, China
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