[CPMD-list] help

[Hyundeok Song]

I want to  unsubscribe the cpmd list

Thanks


Regards
Hyun.

---- Original message ----
>Date: Sat, 23 Feb 2008 11:00:01 +0000
>From: cpmd-list-request at cpmd.org  
>Subject: CPMD-list Digest, Vol 46, Issue 11  
>To: cpmd-list at cpmd.org
>
>Send CPMD-list mailing list submissions to
>	cpmd-list at cpmd.org
>
>To subscribe or unsubscribe via the World Wide Web, visit
>	http://cpmd.org/mailman/listinfo/cpmd-list
>or, via email, send a message with subject or body 'help' to
>	cpmd-list-request at cpmd.org
>
>You can reach the person managing the list at
>	cpmd-list-owner at cpmd.org
>
>When replying, please edit your Subject line so it is more specific
>than "Re: Contents of CPMD-list digest..."
>________________
>Today's Topics:
>
>   1. question about CUTOFF (liu liuxiandong)
>   2. Re: question about CUTOFF (Axel Kohlmeyer)
>________________
>Date: Sat, 23 Feb 2008 00:13:43 +0800
>From: "liu liuxiandong" <xiandongliu at gmail.com>  
>Subject: [CPMD-list] question about CUTOFF  
>To: cpmd-list <CPMD-list at cpmd.org>
>
>Dear CPMD users,
>
>  I want to optimize the geometry of a silicate material. The
>following is part of the input,
>&CPMD	
> RESTART WAVEFUNCTIONS COORDINATES HESSIAN	
> OPTIMIZE GEOMETRY XYZ
> HESSIAN UNIT
>
> CONVERGENCE ORBITALS
> 5.0D-6
> CONVERGENCE GEOMETRY
> 5.0D-4
>
> PCG MINIMIZE
> TIMESTEP
> 10
> LBFGS NREM
> 40
> LSD
>
>&END
>...
>&SYSTEM
>  CUTOFF
>   70.0
>....
>&END
>
>&ATOMS
>
>ISOTOPES
>...
>*O_MT_BLYP.psp KLEINMAN-BYLANDER
> LMAX=P
>*H_MT_BLYP.psp KLEINMAN-BYLANDER
> LMAX=S
>*Si_MT_BLYP.psp KLEINMAN-BYLANDER
> LMAX=D
>*Al_MT_GIA_BLYP.psp KLEINMAN-BYLANDER
> LMAX=D LOC=0
>*Fe_MT_BLYP_NLCC.psp NLCC KLEINMAN-BYLANDER
> LMAX=D LOC=S
>*Na_SEMI_BLYP.psp KLEINMAN-BYLANDER
> LMAX=P
>...............
>The total energy of the relaxed structure is  -983.949852 at CUTOFF 70Ry.
>Then I increased CUTOFF to 75 Ry and performed single-point
>calculation with this optimized structure,  the total energy decreased
>to about -984.845447.
>
>Since such LSD calculation is very time demanding, is it necessary to
>optimize the structure with higher CUTOFF ?
>Thanks.
>
>Xiandong Liu
>
>________________
>Date: Fri, 22 Feb 2008 11:18:04 -0500 (EST)
>From: Axel Kohlmeyer <akohlmey at cmm.chem.upenn.edu>  
>Subject: Re: [CPMD-list] question about CUTOFF  
>To: liu liuxiandong <xiandongliu at gmail.com>
>Cc: cpmd-list <CPMD-list at cpmd.org>
>
>On Sat, 23 Feb 2008, liu liuxiandong wrote:
>
>LX> Dear CPMD users,
>
>dear xiandong,
>
>[...]
>
>LX> ...
>LX> &SYSTEM
>LX>   CUTOFF
>LX>    70.0
>LX> ....
>LX> &END
>
>[...]
>
>LX> The total energy of the relaxed structure is -983.949852 at CUTOFF 
>LX> 70Ry. Then I increased CUTOFF to 75 Ry and performed single-point 
>LX> calculation with this optimized structure, the total energy 
>LX> decreased to about -984.845447.
>
>please note that different properties of your system converge
>differently with the size of the basis set (i.e. the plane wave
>cutoff). for example forces generally converge faster with
>the basis set size than the total energy.
>
>LX> Since such LSD calculation is very time demanding, is it necessary 
>LX> to optimize the structure with higher CUTOFF ?
>
>the required cutoff depends on your desired accuracy and
>the "hardness" of the individual pseudopotentials in your
>system. you don't have to check for the necessary cutoff
>with your whole system, but can check with small subsets.
>just do single points with increasing cutoff and PRINT FORCES
>and see how far your have to go until your forces are
>converged with respect to the accuracy you want. the general
>rule of the thumb is that the forces have to be converged
>roughly two orders of magnitude better than the desired
>accuracy for the geometry optimization. 
>
>with the mix of elements that you have, i would not be
>surprised if you need a cutoff of 90ry or beyond.
>
>cheers,
>   axel.
>
>LX> Thanks.
>LX> 
>LX> Xiandong Liu
>LX> _______________________________________________
>LX> CPMD-list mailing list
>LX> CPMD-list at cpmd.org
>LX> http://cpmd.org/mailman/listinfo/cpmd-list
>LX> 
>
>-- 
>=======================================================================
>Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
>   Center for Molecular Modeling   --   University of Pennsylvania
>Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
>tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
>=======================================================================
>If you make something idiot-proof, the universe creates a better idiot.
>
>________________
>_______________________________________________
>CPMD-list mailing list
>CPMD-list at cpmd.org
>http://cpmd.org/mailman/listinfo/cpmd-list