[Pw_forum] Lattice Constant Optimization of Aluminum

[Paul M. Grant]

Got it...thanks.

Paul M. Grant, PhD
Principal, W2AGZ Technologies
Visiting Scholar, Applied Physics, Stanford University
EPRI Science Fellow (Retired)
IBM Research Staff Member Emeritus
w2agz at pacbell.net
http://www.w2agz.com
 
 


-----Original Message-----
From: pw_forum-admin at pwscf.org [mailto:pw_forum-admin at pwscf.org] On Behalf
Of Paolo Giannozzi
Sent: Thursday, April 26, 2007 12:05 AM
To: pw_forum at pwscf.org
Subject: Re: [Pw_forum] Lattice Constant Optimization of Aluminum


On Apr 26, 2007, at 5:41 , Paul M. Grant wrote:
> Even with a wildly wrong first estimate of celldm(1) of 7.2 (the  
> experimental value at RT is 7.665 au), I get zero net individual  
> atomic forces and thus no optimization.
"optimization wrt internal positions" != "optimization of the lattice  
parameter(s)".
Forces allow the former, stresses the latter. The simplest way to  
optimize the
lattice parameter of a simple crystal is to fit a few E(V) points to  
an equation
of state, using for instance "ev.f90"

Paolo
---
Paolo Giannozzi, Democritos and University of Udine, Italy


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