[Pw_forum] RE: Pw_forum digest, Vol 1 #667 - 4 msgs

Tue Jun 21 15:07:33 CEST 2005

>From: pw_forum-request at pwscf.org
>Reply-To: pw_forum at pwscf.org
>To: pw_forum at pwscf.org
>Subject: Pw_forum digest, Vol 1 #667 - 4 msgs
>Date: Tue, 21 Jun 2005 07:36:33 +0200
>
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>Today's Topics:
>
>    1. Re: need help about PWgui (Gerardo Ballabio)
>    2. Re: temperature oscillations with nose' thermostat (Konstantin 
Kudin)
>    3. Re: temperature oscillations with nose' thermostat (Axel Kohlmeyer)
>    4. Question on how to trace a specific band on nonspecail k-points. 
(=?gb2312?B?1cUguumx8g==?=)
>
>--__--__--
>
>Message: 1
>From: Gerardo Ballabio <g.ballabio at cineca.it>
>Subject: Re: [Pw_forum] need help about PWgui
>To: pw_forum at pwscf.org
>Date: Mon, 20 Jun 2005 11:26:05 +0200 (MEST)
>Reply-To: pw_forum at pwscf.org
>
>On 06/18/05 09:24:54, sun jason wrote:
> > hi,everyone,
> >
> > I installed pwgui on another old computer(redhat 9.0) a few monthes
> > ago, and it launched fast.
> >
> > And now, I installed pwgui-2.1.3 on my new computer, it can be
> > launched, but it is really very very slow, what happened to me? my
> > system is RedHat enterprise linux advance server 4.0, (CPU:
> > pentium4 3.0GHz, mem 1G , display card ATI9550).
>
>Is your problem specific to PWgui, or do you experience slowness also
>on other programs? If the latter, graphical acceleration may not have
>been set up correctly. I've had similar experience with ATI cards.
>Try running "glxinfo" and look if it says "direct rendering: yes" or
>"no".
>
>Gerardo

=============================================================
=============================================================
Yes,you are right, it says "direct redering : no"
Is it the problem?
how can I change the value?

Thank you very much!
==============================================
Jian Sun 
Physics Dept. of Nanjing University 
National Lab. of Solid State Microstructures 
22 Hankou Road, Gulou District 
Nanjing, Jiangsu Province 
210093 
China
==============================================

>--__--__--
>
>Message: 2
>Date: Mon, 20 Jun 2005 08:14:54 -0700 (PDT)
>From: Konstantin Kudin <konstantin_kudin at yahoo.com>
>Subject: Re: [Pw_forum] temperature oscillations with nose' thermostat
>To: pw_forum at pwscf.org,
>	Massimiliano Bonomi <massimiliano.bonomi at mi.infn.it>
>Reply-To: pw_forum at pwscf.org
>
>  If these oscillations concern you, you could run with the Nose-Hoover
>chains in CPV from the current CVS. With the chains the oscillations
>are still present, however, the highs are lower and the lows are
>higher. Thus the plot of temperature vs. time step looks way nicer!
>
>  Kostya
>
>
>--- Massimiliano Bonomi <massimiliano.bonomi at mi.infn.it> wrote:
>
> >   Dear users,
> > I'm running molecular dynamics with fpmd (in espresso v. 2.1.3
> > package)
> > of a solid assembled with cluster of gold.
> > After reaching the electronic ground state i've started the dynamics
> > using nose' thermostat
> > both on ions and electron, choosing the right thermostat frequencies
> > (for ions half the higher phonon frequency, for electrons 2/3 times
> > the
> > higher phonon frequency).
> >
> > During a simulation of 10000 time step (~ 1.0 picoseconds) at T=300K
> >
> > the temperature of the system  made big oscillations around 300K
> > (even
> > of 200K!!).
> >
> > Is it normal?? How can i reduce the width of these oscillations?
> >
> > Best regards and thanks in advance.
> > Massimiliano Bonomi.
> >
> > --
> >
> > Massimiliano Bonomi
> > Dipartimento di Fisica, Universit?degli Studi di Milano
> > via Celoria, 16 - 20133 Milano, Italy
> > ph. +39 02 50317 717
> > e-mail: massimiliano.bonomi at mi.infn.it, massimiliano.bonomi at unimi.it
> >
> >
> > _______________________________________________
> > Pw_forum mailing list
> > Pw_forum at pwscf.org
> > http://www.democritos.it/mailman/listinfo/pw_forum
> >
>
>
>
>
>____________________________________________________
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>--__--__--
>
>Message: 3
>Date: Mon, 20 Jun 2005 17:51:25 +0200 (CEST)
>From: Axel Kohlmeyer <axel.kohlmeyer at theochem.ruhr-uni-bochum.de>
>To: Konstantin Kudin <konstantin_kudin at yahoo.com>
>Cc: pw_forum at pwscf.org,
>	Massimiliano Bonomi <massimiliano.bonomi at mi.infn.it>
>Subject: Re: [Pw_forum] temperature oscillations with nose' thermostat
>Reply-To: pw_forum at pwscf.org
>
>On Mon, 20 Jun 2005, Konstantin Kudin wrote:
>
>dear kostya,
>
>KK>  If these oscillations concern you, you could run with the Nose-Hoover
>KK> chains in CPV from the current CVS. With the chains the oscillations
>KK> are still present, however, the highs are lower and the lows are
>KK> higher. Thus the plot of temperature vs. time step looks way nicer!
>
>two more remarks about this. having low temperature fluctuations is
>not really an important point here. with few atoms (and for AIMD runs
>you basically always have few atoms) the fluctuations _have_ to be
>large. with larger systems they average out more and more, but they
>are still present if you plot the instantaneous temperature/kinetic
>energy of a small subsystem. in fact, you _need_ those fluctuations,
>so that your system can overcome energy barriers. so the fluctuations
>per se are not a bad thing. you should watch out, however, for a
>temperature _drift_. for an MD simulation of 'only' one picosecond,
>there should be (almost) none (provided you are starting in equilibrium).
>
>using nose-hoover thermostat chains is a Good Thing(TM) nevertheless,
>but for a different reason: the nose-hoover chains are a very important
>means to ensure ergodicity, i.e. the fact that that you sufficiently
>explore phase space. the 'normal' nose-hoover does not do that.
>the smaller fuctuations in the total instantaneous temperature
>are just a side effect of that.
>for a system with a small number of atoms (say, less then two hundred),
>you should even have one nose-hoover chain for each degree of freedom.
>a simple example to illustrate that: consider an MD of a single
>water molecule in gas phase. if the starting conditions are selected
>in such a way, that only the bending mode is sufficiently populated,
>it will take a very long time, until the stretch modes are populated,
>since those modes (almost) don't couple to the bending mode.
>
>
>best regards,
>	axel.
>
>KK>  Kostya
>KK>
>KK>
>KK> --- Massimiliano Bonomi <massimiliano.bonomi at mi.infn.it> wrote:
>KK>
>KK> >   Dear users,
>KK> > I'm running molecular dynamics with fpmd (in espresso v. 2.1.3
>KK> > package)
>KK> > of a solid assembled with cluster of gold.
>KK> > After reaching the electronic ground state i've started the dynamics
>KK> > using nose' thermostat
>KK> > both on ions and electron, choosing the right thermostat frequencies
>KK> > (for ions half the higher phonon frequency, for electrons 2/3 times
>KK> > the
>KK> > higher phonon frequency).
>KK> >
>KK> > During a simulation of 10000 time step (~ 1.0 picoseconds) at T=300K
>KK> >
>KK> > the temperature of the system  made big oscillations around 300K
>KK> > (even
>KK> > of 200K!!).
>KK> >
>KK> > Is it normal?? How can i reduce the width of these oscillations?
>KK> >
>KK> > Best regards and thanks in advance.
>KK> > Massimiliano Bonomi.
>KK> >
>KK> > --
>KK> >
>KK> > Massimiliano Bonomi
>KK> > Dipartimento di Fisica, Universit?degli Studi di Milano
>KK> > via Celoria, 16 - 20133 Milano, Italy
>KK> > ph. +39 02 50317 717
>KK> > e-mail: massimiliano.bonomi at mi.infn.it, massimiliano.bonomi at unimi.it
>KK> >
>KK> >
>KK> > _______________________________________________
>KK> > Pw_forum mailing list
>KK> > Pw_forum at pwscf.org
>KK> > http://www.democritos.it/mailman/listinfo/pw_forum
>KK> >
>KK>
>KK>
>KK>
>KK>
>KK> ____________________________________________________
>KK> Yahoo! Sports
>KK> Rekindle the Rivalries. Sign up for Fantasy Football
>KK> http://football.fantasysports.yahoo.com
>KK> _______________________________________________
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>KK> http://www.democritos.it/mailman/listinfo/pw_forum
>KK>
>KK>
>
>--
>
>=======================================================================
>Dr. Axel Kohlmeyer   e-mail: axel.kohlmeyer at theochem.ruhr-uni-bochum.de
>Lehrstuhl fuer Theoretische Chemie          Phone: ++49 (0)234/32-26673
>Ruhr-Universitaet Bochum - NC 03/53         Fax:   ++49 (0)234/32-14045
>D-44780 Bochum  http://www.theochem.ruhr-uni-bochum.de/~axel.kohlmeyer/
>=======================================================================
>If you make something idiot-proof, the universe creates a better idiot.
>
>
>--__--__--
>
>Message: 4
>From: =?gb2312?B?1cUguumx8g==?= <leoant21 at hotmail.com>
>To: pw_forum at pwscf.org
>Date: Tue, 21 Jun 2005 02:42:00 +0000
>Subject: [Pw_forum] Question on how to trace a specific band on nonspecail 
k-points.
>Reply-To: pw_forum at pwscf.org
>
>Dear all:
>   I am trying to plot FermiSurface using .XSF format file, however, I 
find
>it difficult to get the energy value for k-points defined in the .XSF as
>general grid: you see, when one plot band structure, one get the energy
>values for serial special k-points, and get them proceeded by bands.x and
>plot the band structure through plotband.x; however, as to "general grid"
>defined in reciprocal space in .XSF file, though I can calculate a lot of
>energy values, how can I trace the energy values belong to specific band 
on
>the non special k-points, since energy may vary greatly?
>   Or is there any good way to plot the Fermi Surface of realistic
>materials?
>Thanks in advance.
>Regards.
>
>_________________________________________________________________
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>End of Pw_forum Digest