[lammps-users] hybrid Tersoff/Buckingham potential

Dear all,

I would like to use hybrid Tersoff and Buckingham potential for a ternary elements (A,B,C) system. The following is the corresponding code in input file,

pair_style hybrid/overlay tersoff buck/coul/long 10.0
pair_coeff 12 12 tersoff sico-nocosi.tersoff A B C
kspace_style pppm 1.0e-4 #for Coulombic items calculation
pair_coeff 1 3 buck/coul/long 18003.7572 0.205205 133.5381
pair_coeff 3 1 buck/coul/long 18003.7572 0.205205 133.5381
pair_coeff 2 3 buck/coul/long 18003.7572 0.205205 133.5381
pair_coeff 3 2 buck/coul/long 18003.7572 0.205205 133.5381
pair_coeff 3 3 buck/coul/long 1388.7730 0.362319 175.0

But I always received the info ’ Incorrect args for pair coefficients’. Does anybody has idea on how should I write the code here?

Thanks a lot.

Tom

pair_coeff 1*2 1*2 tersoff sico-nocosi.tersoff A B C

The Tersoff doc page explains that you must use * * for
the types in this command.

Steve

2010/6/16 YuTom <[email protected]>:

Steve, thanks for reply. So is there any other option to realize this kind of Tersoff/Buckingham combination?

Tom

在2010-06-17 22:08:52,"Steve Plimpton" <[email protected]> 写道:
>> pair_coeff 1*2 1*2    tersoff sico-nocosi.tersoff A B C
>
>The Tersoff doc page explains that you must use * * for
>the types in this command.
>
>Steve
>
>2010/6/16 YuTom <[email protected]>:
>> Dear all,
>>
>> I would like to use hybrid Tersoff and Buckingham potential for a ternary
>> elements (A,B,C) system. The following is the corresponding code in input
>> file,
>>
>> pair_style    hybrid/overlay tersoff buck/coul/long 10.0
>> pair_coeff 1*2 1*2    tersoff sico-nocosi.tersoff A B C
>> kspace_style  pppm 1.0e-4   #for Coulombic items calculation
>> pair_coeff 1 3 buck/coul/long 18003.7572 0.205205 133.5381
>> pair_coeff 3 1 buck/coul/long 18003.7572 0.205205 133.5381
>> pair_coeff 2 3 buck/coul/long 18003.7572 0.205205 133.5381
>> pair_coeff 3 2 buck/coul/long 18003.7572 0.205205 133.5381
>> pair_coeff 3 3 buck/coul/long 1388.7730 0.362319 175.0
>>
>> But I always received the info ' Incorrect args for pair coefficients'. Does
>> anybody has idea on how should I write the code here?
>>
>> Thanks a lot.
>>
>> Tom
>>
>>
>>
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>>
>>

You haven't explained what it is you are trying to do.
The pair hybrid (or overlay) doc page explains what
it means to use a manybody potential like Tersoff as
part of the hybrid command. You cannot specify
Tersoff for atom types 1,2,3 and then "turn-off" the
Tersoff between types 2-3 only. That is not what
a many body potential means.

Steve

2010/6/18 Tom Yu <[email protected]>:

I would like to try two cases:

  1. use Tersoff just for 1 and 2 (include 11 12 22), and use Buckingham for the rest (13 22 23 33). This means I do not want to just turn off the 23 interaction only, but to turn off all the interactions related to 3, as the Tersoff potential is only good at modeling of 12 system.
  2. use Tersoff for all the elements, and use Buckingham for some of the interactions too. in this case, there are some overlaps.

在2010-06-19 22:11:43,"Steve Plimpton" <[email protected]> 写道:
>You haven't explained what it is you are trying to do.
>The pair hybrid (or overlay) doc page explains what
>it means to use a manybody potential like Tersoff as
>part of the hybrid command.  You cannot specify
>Tersoff for atom types 1,2,3 and then "turn-off" the
>Tersoff between types 2-3 only.  That is not what
>a many body potential means.
>
>Steve
>
>2010/6/18 Tom Yu <[email protected]>:
>> Steve, thanks for reply. So is there any other option to realize this kind
>> of Tersoff/Buckingham combination?
>> Tom
>>
>> 在2010-06-17 22:08:52,"Steve Plimpton" <[email protected]> 写道:
>>>> pair_coeff 1*2 1*2    tersoff sico-nocosi.tersoff A B C
>>>
>>>The Tersoff doc page explains that you must use * * for
>>>the types in this command.
>>>
>>>Steve
>>>
>>>2010/6/16 YuTom <[email protected]>:
>>>> Dear all,
>>>>
>>>> I would like to use hybrid Tersoff and Buckingham potential for a ternary
>>>> elements (A,B,C) system. The following is the corresponding code in input
>>>> file,
>>>>
>>>> pair_style    hybrid/overlay tersoff buck/coul/long 10.0
>>>> pair_coeff 1*2 1*2    tersoff sico-nocosi.tersoff A B C
>>>> kspace_style  pppm 1.0e-4   #for Coulombic items calculation
>>>> pair_coeff 1 3 buck/coul/long 18003.7572 0.205205 133.5381
>>>> pair_coeff 3 1 buck/coul/long 18003.7572 0.205205 133.5381
>>>> pair_coeff 2 3 buck/coul/long 18003.7572 0.205205 133.5381
>>>> pair_coeff 3 2 buck/coul/long 18003.7572 0.205205 133.5381
>>>> pair_coeff 3 3 buck/coul/long 1388.7730 0.362319 175.0
>>>>
>>>> But I always received the info ' Incorrect args for pair coefficients'. Does
>>>> anybody has idea on how should I write the code here?
>>>>
>>>> Thanks a lot.
>>>>
>>>> Tom
>>>>
>>>>
>>>>
>>>> ________________________________
>>>> 网易为中小企业免费提供企业邮箱(自主域名)
>>>> ------------------------------------------------------------------------------
>>>> ThinkGeek and WIRED's GeekDad team up for the Ultimate
>>>> GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the
>>>> lucky parental unit.  See the prize list and enter to win:
>>>> http://p.sf.net/sfu/thinkgeek-promo
>>>> _______________________________________________
>>>> lammps-users mailing list
>>>> [email protected]
>>>> https://lists.sourceforge.net/lists/listinfo/lammps-users
>>>>
>>>>
>>
>>
>>

1) can be done with pair_style hybrid
2) can be done with pair_style hybrid/overlay

In the first case just defined Tersoff for types 1,2 and set type 3 to NULL
in the pair_coeff command for Tersoff. Then add your Buck for the
other interactions

In the second case, define Tersoff for all types 1,2,3
Then add Buck on top of it.

Steve

2010/6/21 Tom Yu <[email protected]>:

Hi, Steve, I just tried the first case, but always got “ERROR: Invalid pair style”. The following is the input file,


units metal
atom_style charge
pair_style hybrid buck/coul/long 10.0 tersoff
pair_coeff 1 3 buck/coul/long 18003.7572 0.205205 133.5381
pair_coeff 2 3 buck/coul/long 18003.7572 0.205205 133.5381
pair_coeff 3 3 buck/coul/long 1388.7730 0.362319 175.0
pair_coeff * * tersoff sico.tersoff Si C NULL

kspace_style pppm 1.0e-4 #for Coulombic items calculation

Is this related to the atom_style? I am not sure if the ‘charge’ option can be used for Tersoff potential.

Tom

If I run this input script with the current LAMMPS I get no errors.
Did you bulid LAMMPS with the 2 pair styles that you are using?
E.g. are they in your src dir?

Steve

units metal
atom_style charge

lattice fcc 0.8442
region box block 0 5 0 5 0 5
create_box 3 box

pair_style hybrid buck/coul/long 10.0 tersoff

pair_coeff 1 3 buck/coul/long 18003.7572 0.205205 133.5381
pair_coeff 2 3 buck/coul/long 18003.7572 0.205205 133.5381
pair_coeff 3 3 buck/coul/long 1388.7730 0.362319 175.0
pair_coeff * * tersoff ../potentials/SiC.tersoff Si C NULL

kspace_style pppm 1.0e-4 #for Coulombic items calculation

2010/8/17 Tom Yu <[email protected]>: