Source code doubt

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1

Hi all

I am trying to understand pair_dpd.cpp for further clarifications on my project. On line 107 there is a statement j & = NEIGHMASK. Could anyone please help me in understanding what precisely does this line do. I did not see the definition of NEIGHMASK or anything pointing to that in the code. I understood that it has to do something with neighbor list, but could not understand it properly. Any guidance as to what needs to be looked at would be appreciated.

Regards

Vaidyanathan M S

2

Hi all

I am trying to understand pair_dpd.cpp for further clarifications on my
project. On line 107 there is a statement j & = NEIGHMASK. Could anyone
please help me in understanding what precisely does this line do. I did not
see the definition of NEIGHMASK or anything pointing to that in the code. I

[[email protected]... src]$ grep NEIGHMASK *.h
lmptype.h:#define NEIGHMASK 0x3FFFFFFF

understood that it has to do something with neighbor list, but could not
understand it properly. Any guidance as to what needs to be looked at would
be appreciated.

this two highest bits in the neighbor list entries are use to encode
if an atom is a 1-2, 1-3, or 1-4 neighbor. the line of code you are
referring to clears these bits unconditionally, so that you have a
valid "j". almost all of these kind of things are explained somewhere
in the comments in header files.

i strongly recommend to practice using "grep" to locate items if interest.

axel.

3

Thanks Axel. Thanks for the tip as well

Regards

Vaidyanathan M S