(no subject)

hello users,

i have defined two regions in my simulation and ,want to calculate msd(meansquaredisplacement
)for this two regions,but unable to calculate it separately for cations and anions,as my both region contains cations and anions both .

do anybody has idea how should i write msd command so that that i can calculate anion.msd and cation.msd both for wall and bulk regions.???

region bulk block 46 70 0 50 -12 42
region wall block 80 120 0 50 -12 42

compute mymsd1 wall msd com yes
fix mymsd1 wall ave/time 1 1 500 c_mymsd1[4] file wall.msd

compute mymsd2 bulk msd com yes
fix mymsd2 bulk ave/time 1 1 500 c_mymsd2[4] file bulk.msd

help!!!

some general comments:

  • please make it a habit to use a meaningful subject line on your e-mails. this will significantly increase the chances that people read them and thus your chances to get help
  • there is no point in copying steve or me when you send an e-mail to lammps-users. we are both subscribed and will receive e-mails from the list. due to copying us, you just make it more effort to have your e-mail automatically sorted into the proper mail folder.

Thanks for the sugesstions,
BUT i have already mention the groups,and i have cations and anions both in wall and bulk region,how to get cations and anions both in wall and bulk region,how can i calculate msd by specifying two groups.[group wall region wall
group bulk region bulk+group cation type group anion type]

region bulk block 46 70 0 50 -12 42
region wall block 80 120 0 50 -12 42

group wall region wall

group bulk region bulk

group cation type 1 2 3 4

group anion type 8

compute mymsd1 wall msd com yes
fix mymsd1 wall ave/time 1 1 500 c_mymsd1[4] file wall.msd

compute mymsd2 bulk msd com yes
fix mymsd2 bulk ave/time 1 1 500 c_mymsd2[4] file bulk.msd

You can make 4 groups:

cations in region sall
cations is region bulk
ditro for anions

Then 4 compute msd commands.

Or use different atom types for wall vs bulk
atoms and setup the groups based on atom types.
Etc.

Steve

thanks a lot sir!!

Respected sir,

As u told

cations in region sall
cations is region bulk
ditro for anions

Then 4 compute msd commands.

Or use different atom types for wall vs bulk
atoms and setup the groups based on atom types.
Etc.

but how to specify the cations in region bulk and region wall as i already specify that

region bulk block 46 70 0 50 -12 42
region wall block 80 120 0 50 -12 42

group wall region wall

group bulk region bulk

my cations are both in wall and bulk region how can i group

group cationbulk type 1…how can i specify both as region and type??