[AMBER] QMMM SCC-DFTB: ERROR ON EWEVGE (Eigenvalue solver)

From: Kanin Wichapong <kanin.wichapong.gmail.com>
Date: Tue, 14 Jan 2014 15:24:47 +0100

Dear Amber Users,

I tried to set up QM/MM calculation using scc-dftb method. I downloaded the
scc-dftb parameters (3ob set) from the dftb website (www.dftb.org).
However, I got an error about Eigenvalue solver during the calculation.

Here is my input:

Minimization ENTIRE COMPLEX ---

&cntrl

imin = 1,

maxcyc = 5000,

ncyc = 2500,

ntb = 1,

ntr = 0,

cut = 8

ifqnt = 1

/

&qmmm

qmmask=":42,191,266,267,397 ",

qm_theory='DFTB',

dftb_disper=1,

dftb_chg=1,

tight_p_conv=1,

scfconv=1.0d-8,

qm_ewald=1,

qmcharge=2,

/

The QM region includes Ser, His, Water (protein), and Arg-Lys (substrate).


Here is the error:

*NSTEP ENERGY RMS GMAX NAME NUMBER *

*1 -2.6303E+05 2.5691E+00 1.4419E+02 NZ 4186 *

 *BOND = 20291.2616 ANGLE = 1875.4936 DIHED = 6004.3320 *

*VDWAALS = 51206.9170 EEL = -347214.0714 HBOND = 0.0000 *

*1-4 VDW = 1303.0030 1-4 EEL = 12384.0272 RESTRAINT = 0.0000 *

*DFTBESCF= -8884.5851 *

 *QMMM SCC-DFTB: *************************************************** *

*QMMM SCC-DFTB: ERROR ON EWEVGE (Eigenvalue solver). *

*QMMM SCC-DFTB: ewevge: ier = 193 inner_scf_count= 1 *

*QMMM SCC-DFTB: *************************************************** *

 *QMMM SCC-DFTB: !!!! ============= WARNING ============= !!!! *

*QMMM SCC-DFTB: Convergence could not be achieved in this step. *

*QMMM SCC-DFTB: The calculation will continue, but energies and *

*QMMM SCC-DFTB: forces for this step will not be accurate. *

I also tried not to include water in the QM region, but I still got the
same error. However, if I used other QM methods (AM1, PM3 or PM6), the
calculation was fine, no error. I found in the amber-mailing list that
somebody also had the same problems as me but there were no clear solutions
to solve this problems on that time.


 I hope that somebody can help me to solve this problems.


 Best Regards and Thank you so much in advance,

Kanin Wichapong
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Received on Tue Jan 14 2014 - 06:30:03 PST
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