AMBER Archive (2006)

Subject: Re: AMBER: Nmode memory allocation error ?

From: David A. Case (
Date: Tue Apr 11 2006 - 14:09:26 CDT

On Tue, Apr 11, 2006, Junmei Wang wrote:

> Total memory required : 88254278 real words
> ASSERTion 'ier == 0' failed in nmode.f at line 105.

The system is failing to allocate 88 million double precision words, which is
about 700 Mbytes. How much memory is available on your system? There is
really not much you can do about this, except configure the system to have
more memory (including adjusting your swap space).

Or, one might ask: "why do you want to do a Newton-Raphson minimization on
a 3000 atom system?"

The nmode program was written in 1982 or so, with the idea of running on
systems of about 300 atoms or less. Its more up-to-date equivalent is NAB
(see the web site below): we have carried out NR minimization and normal modes
on systems with as many as 45,000 atoms -- but that was on supercomputers,
not on workstations that couldn't allocate 700 Mbytes of memory.

...good luck...dac

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