Regarding Regions

Dear all,
When Newtonian atoms, thermal atoms and boundary atoms are defined, Is there any compulsion on them to be in integers.

Like if my lattice constant is 5.43095
for specifying boundary in lattice units :- region TA block 0.0 0.5533 0.5533 10.3111 inf inf
Horizontal and vertical length makes to integers.

I am asking this question because if I take them in non-integers, the atoms are losing their position.

Regards

The region command can be defined with floating point values.

Whether that makes sense wrt how you are using the region,

is up to you to decide.

the atoms are losing their position.

Not clear what this means.

Steve

Hi,
there is no doubt that region command can take floating point values.

But while taking them in floating points in lattice units, they will give a floating point value (lattice X floating value) of the regional distance also.
Now, In one simulation i find if that regional distance (lattice constant X floating value in the command) is a floating value, atoms starts flying and spoils the simulation.

region TA block 0.0 0.5533 0.5533 10.3111 inf inf

lattice constant is 5.43095

0.5533x5.43 = 3 , (10.3111-0.5533)x5.43 = 53
like here i have box size in x and y is 3 and 53 approx i.e. in integers.

If i take
region TA block 0 1 1 10 inf inf

box size in x 5.43 ( 5.43 x 1 )
box size in y 48.87 ( (10-1) x 5.43)

these are non-integers.
In this case atoms are flying from that box.

Hi,
there is no doubt that region command can take floating point values.

But while taking them in floating points in lattice units, they will give a
floating point value (lattice X floating value) of the regional distance
also.
Now, In one simulation i find if that regional distance (lattice constant X
floating value in the command) is a floating value, atoms starts flying and
spoils the simulation.

it won't be due to whether you use floating point or integer values on
your regions, but whether you have close contacts, i.e. generate atoms
on initial positions that will result in very large forces due to
proximity. that can happen either way. it is a matter of care when
building your system. it is usually avoided by defining regions so
they won't begin and terminate on or close to lattice points.

axel.

Could you try the following?

region TA block 0.1 1.1 1.1 10.1 inf inf

Ray