[CPMD-list] Si geometry optimization test

[Juerg Hutter]

Hi

you have obviously to use a norm-conserving Pseudopotential,
for example

*Si_MT_PBE.psp KLEINMAN-BYLANDER
    LMAX=D

Another observation: now you put 64 silicon atoms into
a cubic cell of 10.28 Bohr^3 volume. This is off the
equilibrium by a factor of 8 in volume. The correct
box length for this number of atoms is 20.526204 Bohr.

regards

Juerg Hutter

----------------------------------------------------------
Juerg Hutter                   Phone : ++41 44 635 4491
Physical Chemistry Institute   FAX   : ++41 44 635 6838
University of Zurich           E-mail: hutter at pci.unizh.ch
Winterthurerstrasse 190
CH-8057 Zurich, Switzerland
----------------------------------------------------------


On Mon, 1 May 2006, Emre Ersin wrote:

> Hi,
> I've changed my input file as follows;
>
> &INFO
> Bulk Si
> GeoMetry Optimization
> &END
>
> &CPMD
>  ODIIS NO_RESET=50
>  5
>  OPTIMIZE GEOMETRY XYZ
>  CONVERGENCE INITIAL
>   1.0d-4
>  CONVERGENCE GEOMETRY
>   1.0d-3
>  CONVERGENCE ORBITALS
>   1.0d-7
>  CONVERGENCE ADAPT
>   0.02
>  CONVERGENCE ENERGY
>   0.05
>  STEEPEST DESCENT CELL
>  BFGS
> &END
>
> &SYSTEM
>  SYMMETRY
>  1
>  SCALE
>  ISOTROPIC CELL
>  CELL
>  10.25 1.0 1.0 0.0 0.0 0.0
>  CUTOFF
>  20.0
> &END
>
> &DFT
> FUNCTIONAL GGA
> &END
>
> &ATOMS
> *SI.USP FORMATTED
>   LMAX=p
>   64
> 0.000   0.000   0.000
> 0.250   0.250   0.000
> 0.250   0.000   0.250
> ...
>
>
> And got this error message;
> ...
> 172  1.140E-03   1.549E-05     -82.186623   -2.278E-05      0.94
> 173  9.196E-04   1.910E-05     -82.186606    1.684E-05      0.95
> 174  7.912E-04   9.867E-06     -82.186600    5.913E-06      0.94
> 175  8.565E-04   9.753E-06     -82.186603   -2.427E-06      0.95
> 176  7.203E-04   1.390E-05     -82.186584    1.886E-05      0.94
> 999
> 177  2.087E-04   4.571E-06     -82.186581    2.910E-06      0.95
> STOPGM! STACK OF MAIN CALLS:
> STOPGM! CALL    FORCEDR
> STOPGM! CALL     FORCES
> STOPGM! CALL     STRESS
>
>
> PROGRAM STOPS IN SUBROUTINE STRESS| STRESS TENSOR IS BROKEN FOR VANDERBILT
> USPP
>
> Is there anything that I can do with my input file to not to get this
> message?
> Emre
>
> -----Original Message-----
> From: Juerg Hutter [mailto:hutter at pci.unizh.ch]
> Sent: Friday, April 28, 2006 3:15 PM
> To: Emre Ersin
> Cc: cpmd-list at cpmd.org
> Subject: Re: [CPMD-list] Si geometry optimization test
>
> Hi
>
> the box length of silicon in a simple cubic lattice is
> 10.28 Bohr, not 6 Bohr as in your input.
>
> The FCC structure of silicon in a 8 atom supercell is
> not stable, unless you are using k-points.
> You have to go to at least a 16 atom supercell to
> stabilize the structure in a Gamma point calculation.
>
> I assume you plan to go to other systems and therefore
> want to test USPPs. For silicon alone, any norm-conserving
> PP would be also ok at 20 Rydberg cutoff.
>
> regards
>
> Juerg Hutter
>
>
> ----------------------------------------------------------
> Juerg Hutter                   Phone : ++41 44 635 4491
> Physical Chemistry Institute   FAX   : ++41 44 635 6838
> University of Zurich           E-mail: hutter at pci.unizh.ch
> Winterthurerstrasse 190
> CH-8057 Zurich, Switzerland
> ----------------------------------------------------------
>
>
> On Fri, 28 Apr 2006, Emre Ersin wrote:
>
>> Hi,
>>
>> I am working on geometry optimization of Bulk Si crystal as a beginning
>> project.  I am using Vanderbild USPP-735 and cpmd 3.11 (RHEL amd
>> x86_64-ifort) . Results in my GEOMETRY.xyz file are completely wrong. What
>> can I do about this?
>>
>> Thanks in advance
>>
>>
>> Result (GEOMETRY.xyz):
>> -------------------------------------
>>       8
>> GEOMETRY FILE / created by CPMD
>> Si     -0.095815486591     -0.211103768459     -0.530135268170
>> Si      0.399347278859      1.647314818387     -0.616958156691
>> Si      1.601381554440     -0.889147011651      1.794392840814
>> Si     -0.564859054511      0.740283773580      1.553802768307
>> Si      0.311613943292      0.714749168784      0.493894683966
>> Si      1.487911875733      2.356276096179      0.300978024842
>> Si      1.278324047112      0.698727831026      2.082213155523
>> Si     -0.195579241049      2.358727516743      1.058717791456
>>
>>
>> My Input file is;
>> ----------------------
>>
>> &INFO
>> Bulk Si
>> GeoMetry Optimization
>> &END
>>
>> &CPMD
>>  ODIIS NO_RESET=100
>>  5
>>  HESSIAN UNITY
>>  OPTIMIZE GEOMETRY XYZ
>>  CONVERGENCE INITIAL
>>   1.0d-4
>>  CONVERGENCE GEOMETRY
>>   1.0d-3
>>  CONVERGENCE ORBITALS
>>   1.0d-7
>>  CONVERGENCE ADAPT
>>   0.02
>>  CONVERGENCE ENERGY
>>   0.05
>>  BFGS
>> &END
>>
>> &SYSTEM
>>  SYMMETRY
>>  1
>>  SCALE
>>  ISOTROPIC CELL
>>  CELL
>>  6.0 1.0 1.0 0.0 0.0 0.0
>>  CUTOFF
>>  20
>> &END
>>
>> &DFT
>> FUNCTIONAL GGA
>> &END
>>
>> &ATOMS
>> *SI.USP FORMATTED
>>   LMAX=p
>>   8
>> 0       0       0
>> 0.5     0.5     0
>> 0.5     0       0.5
>> 0       0.5     0.5
>> 0.25    0.25    0.25
>> 0.75    0.75    0.25
>> 0.75    0.25    0.75
>> 0.25    0.75    0.75
>>
>> &END
>>
>> ---
>>
>> Emre Ersin
>>
>> _______________________________________________
>> CPMD-list mailing list
>> CPMD-list at cpmd.org
>> http://cpmd.org/mailman/listinfo/cpmd-list
>>
>
>