AMBER Archive (2008)

Subject: Re: AMBER: Ewald PARAMETER RANGE WRONG

From: David A. Case (case_at_scripps.edu)
Date: Mon May 12 2008 - 11:00:44 CDT

On Sun, May 11, 2008, WANG,YING wrote:

> When I run a simulation without periodic boundary condition and in
> vacumm enviroment, the simulation stop because the error as
> below:
>
> Ewald PARAMETER RANGE CHECKING:
> parameter a: (unit cell size) has value 0.10991E+04
> This is outside the legal range
> Lower limit: 0.10000E+01 Upper limit: 0.10000E+04
> Check ew_legal.h
>
> could anybody tell me how to fix it? Thanks a lot!

Amber is not really set up to do vacuum calculations. It sets up a dummy
periodic box around the system (but with no images). If the system changes it
shape a lot, it can move outside that box, and cause the error you see.

If you can't avoid having your system move a lot, you can also run a
simulation with ntb=0 and igb=6. But be sure to check to see if your
simulation is not doing something you don't want, such that it won't fit into
a 1000 A box.

...dac

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