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Loic Joubert-Doriol
loic.joubert.doriol@gmail.com

I am trying to optimize the geometry of a large molecular system while constraining some atomic positions and dihedral angles at the MCSCF level. The full system comprises two molecules so I also have to include a NONVDW pair of atoms.

It does not converge at all, the energy and the gradient oscillate.
It is the first time I am trying doing such optimization and I am wondering if I am using the right combination of keywords so I give them here:
"
$CONTRL
 SCFTYP=MCSCF  RUNTYP=optimize  MAXIT=150  ICHARG=-1
 MULT=1  UNITS=angstrom   fstint=.t. gencon=.t. NZVAR=198 EXETYP=run
$END
$MCSCF
 CISTEP=GUGA SOSCF=.T. FULLNR=.F. FCORE=.F. istate=1 maxit=100 ntrack=3
 fors=.t. CHKPOP=.FALSE. acurcy=5d-8 ENGTOL=5.0d-13 MICIT=20
$END
$TRACK $END
$ZMAT
 DLC=.TRUE. AUTO=.TRUE. NONVDW(1)=15,60
 IFZMAT(1)= 3, 6,7,2,17,   3, 7,6,19,18, 3, 5,6,7,2,  3, 8,7,6,19,  3, 7,6,5,10
 IFZMAT(26)=3, 6,7,8,9,    3, 7,8,9,10,  3, 6,5,10,9, 3, 8,9,10,14, 3, 5,10,9,11
 IFZMAT(51)=3, 9,10,14,13, 3, 10,9,11,12
 IFRZAT(1)= 3,15,16,35,43,60,61
 DLCTOL=1D-7 ORTTOL=1D-7 IFDMOD=0
$END
$STATPT OPTTOL=0.0001 method=gdiis NSTEP=50 HSSEND=.t. FMAXT=100 $END
...
"

Has anyone any idea on any wrong keyword combinations I am using and/or if there are ways to solve this problem?

Thanks in advance for any help.

Regards,
Loïc Joubert-Doriol.