# lj to real unit conversion of distance !

Hi,
I am using DPD simulation with lj style, and has a box size defined as following-

-23.2079441681 23.2079441681 xlo xhi
-23.2079441681 23.2079441681 ylo yhi
-23.2079441681 23.2079441681 zlo zhi

Now, if convert a side of this box (e.g. 46) in real units, it should be, distance = 46* sigma = 46 Angstrom, according to the conversion factors mentioned in the section of ‘LAMMPS units’. However, the obtained length scale in real unit does not seem to be sensible for the polymeric system that I am coarse-graining. Hence, it will be much appreciated if someone can, please, shed some light on whether I am missing any dot here.

Sincerely,
Tuhin

Hi,
I am using DPD simulation with lj style, and has a box size defined as
following-

-23.2079441681 23.2079441681 <(207)%20944-1681> xlo xhi
-23.2079441681 23.2079441681 <(207)%20944-1681> ylo yhi
-23.2079441681 23.2079441681 <(207)%20944-1681> zlo zhi

Now, if convert a side of this box (e.g. 46) in real units, it should be,
distance = 46* sigma = 46 Angstrom, according to the conversion factors
mentioned in the section of 'LAMMPS units'. However, the obtained length
scale in real unit does not seem to be sensible for the polymeric system
that I am coarse-graining. Hence, it will be much appreciated if someone
can, please, shed some light on whether I am missing any dot here.

​the conversion factor is indeed your reference sigma, but you have to
multiple with that sigma provided _in real units_.
it will probably be easier to understand, if you consider how you get from
real units to reduced units.

axel.