Perhaps relevant to add to the issue below:
---solvateCap EQE TIP3PBOX {coordinates of a solute central atom} 20.0
placed the solute right at the center of the spherical cap; though, along the
longer axis, the 98-atoms solute was not far from the spherical cap edge. I
wonder whether a much bigger cap should be set, and whether 20.0 present one
has hindered SCC convergence.
--- I was surprised that DFTB MD used as as little memory as AM1 MD (ca 0.1% of
the 4GB available per node). Having not yet read the DFTB theory in detail, I
am comparing to classical DFT, where modern functionals at modest 6-31G* basis
set level, with the same 98-atoms molecule in vacuum, led to use all the
available memory (ad there was still much swapping). I understand that DFTB
working must be profoundly different from classical DFT.
francesco
--- Francesco Pietra <chiendarret.yahoo.com> wrote:
> Date: Sat, 25 Aug 2007 10:54:12 -0700 (PDT)
> From: Francesco Pietra <chiendarret.yahoo.com>
> Subject: SCC convergence failure in QM-MM DFTB
> To: Amber <amber.scripps.edu>
>
> Now the 98-atoms solute is well inside TIP3PBOX cap (prepin from
> antechamber).
> After successful minimization with:
>
> Initial min for qmmm with dftb
> &cntrl
> imin=1, maxcyc=500, ncyc=200,
> cut=20.0, ntb=0, ntc=2, ntf=2,
> ivcap=0, fcap=10,
> ifqnt=1
> /
> &qmmm
> qmmask=':1',
> qmcharge=0,
> qmtheory=7,
> qmshake=0,
> qm_ewald=0
> /
>
> MD with:
>
> 300K constant temp for qmmd with dftb
> &cntrl
> imin=0, ntb=0
> cut=20.0, ntc=2, ntf=2,
> tempi=300.0, temp0=300.0,
> ntt=3, gamma_ln=1.0,
> nstlim=20000, dt=0.002,
> ivcap=0, fcap=10,
> ntpr=100, ntwx=100,ifqnt=1
> /
> &qmmm
> qmmask=':1',
> qmcharge=0,
> qmtheory=7,
> qmshake=0,
> qm_ewald=0
> /
>
> sander.MPI (mpirun -np 4) exited because:
>
> vlimit exceeded for step 2886; vmax = 26.4356
> SANDER BOMB in subroutine eglcao <qm2_dftb_eglcao.f> :
> SCC Convergence failure - MAXITER exceeded.
> Exiting
>
> Much obliged for suggestions what to do best. Thanks
>
> francesco pietra
>
>
>
>
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Received on Wed Aug 29 2007 - 06:07:03 PDT
