lj/cut args

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1

Hi All,

I have been confused about lj/cut args. In the manual it is written that lj/cut args = cut off and cut off = global cut off for LJ interactions ( distance units). This game me an impression that args should be 2.5, but I see an examples where they use 7.5 as a global cut off. I guess that I am missing something. I would appreciate if someone can answer my question or can send me a link where it is explained.

Thanks,
Rose

2

Hi All,

I have been confused about lj/cut args. In the manual it is written that lj/cut args = cut off and cut off = global cut off for LJ interactions ( distance units). This game me an impression that args should be 2.5, but I see an examples where they use 7.5 as a global cut off. I guess that I am missing something. I would appreciate if someone can answer my question or can send me a link where it is explained.

why should the cutoff by (only) 2.5 (and 2.5 in what units)?

i and many others have used and will use many different values for the
cutoff varying over a wide range of values depending on the details of
the specific system, the model and the choice of units.

for any additional information, i suggest you review your text book on
MD where it describes the reason for using a cutoff and how a suitable
value is chosen.

axel

3

As Axel said, note that the 2.5 or 7.5 are in distance units.

The units command is often different in different input scripts.

2.5 is a typical value for LJ units. 7.5 is typical

for real or metal units, since distance = Angstroms.

Steve

4

Thank you Axel and Steve.

Rose