# To find the centre of the simulation box

Is there any trick in order to find the centre of the box we have generated? For example, I have created a simulation box of -
lattice diamond 3.4
region diamondBox block 0 10 0 10 0 10

Then where should I define the cylindrical region?

Also in the code i have used the “real” units so the dimensions of the block must be in Angstrom. The CNT which I have made has chirality (3,3) - armchair configuration and length of 2.467nm, i.e. 24.67 Angstrom. I have to make the length of matrix in the same direction of CNT as 34 Angstrom. But when I’m putting these values, the difference in the sizes of CNT and simulation box is too much. Can u tell any reason for it?

Is there any trick in order to find the centre of the box we have generated?

you can compute the center of a simulation cell from an equal style (or immediate) variable expression. those have access to all thermo output keywords. so the x coordinate of the center would be: \$(xlo+0.5*lx)

For example, I have created a simulation box of -
lattice diamond 3.4
region diamondBox block 0 10 0 10 0 10

Then where should I define the cylindrical region?

Also in the code i have used the “real” units so the dimensions of the block must be in Angstrom. The CNT which I have made has chirality (3,3) - armchair configuration and length of 2.467nm, i.e. 24.67 Angstrom. I have to make the length of matrix in the same direction of CNT as 34 Angstrom. But when I’m putting these values, the difference in the sizes of CNT and simulation box is too much. Can u tell any reason for it?

i don’t understand what you are saying here. rather than describing what you do, why don’t you give the exact input lines and what you get as a result and what you want to have or how you determined the mismatch you observe.

axel.