Subject: SUMARY : G92 ECP and F functions

From: <[email-masked]>
Date: Thu, 14 Mar 1996 09:54:21 +0100

Hello,

Two weeks ago I posted a question to the list.
Here is the sumary of the answers I got :

My question was :

I had troubles with trying to optimize a geometry
with g92 (RevE.2).
I'm trying to optimize a geometry at the HF level
using the Berny algorithm.
A RECP describe the core electrons of the metal and it contains
G,S-G,P-G,D-G,F-G components.
The basis set associated with this RECP is a [3s,3p,2d,2f]
GTF basis set.
I've no troubles to perform single point calculations but the
optimization lead to the following error message :

------
RHF calculation of E
------
 Compute integral first derivatives.
 ... and contract with generalized density number  0.
 Use density number 0.
 RysSet:  KIntrp=     2534   KCalc=        0   KAssym=     2170
 L702 exits ... SP integral derivatives will be done elsewhere.
 Compute integral first derivatives.
 Integral derivatives from FoFDir, PRISM(SPDF).
 MinBra= 0 MaxBra= 3 MinLOS=-1 MaxLOS=-1 MinRaf= 0 MaxRaf= 3 MinLRy= 4.
 IRaf=       0 NMat=   1 IRICut=       1 DoRegI=T DoRafI=F ISym2E=1 JSym2E=1.
 Fock matrices symmetrized in FoFDir.
 Use density number 0.
 MaxL=3 MaxP=3 NDeriv=1 MaxT=77
 L709 cannot do derivatives in this basis.
 Error termination in Lnk1e.

------
 
The error is arrising from the l709 link
I've looked at the code and it cames from the ECPGRD Subroutine
wich compute the derivatives of one electron integrals over effective
core potentials.
I looked at the manual and found nothing...
I've tried other tests and my believe is that it is not possible to
have F function describing the valence electrons of the metal
if you have a ECP (or RECP) for the core and if you intend to
optimize a geometry.
So my question is :
Does anybody know such limitations with g92 and ECP ?
More what are the limits in term of component (S,P,D,F)
of a basis set for an atom ?.
Does anybody know if this problem could be avoided with
g94 ?.
So any help or comment would be appreciated.
I will sumarize for the list.
 
THE ANSWERS ARE :

*****************************************************************
From Kazuo Teraishi :
*****************************************************************

I just encountered exactly the same problem with gaussian 94.
I think there are some limitations with ECP which are not mentioned
in the manual. Another limitation I came accross was the 
calculation of analytical second derivatives with ECP.

E-mail : [email-masked]

*****************************************************************
From Dr. David Danovich
*****************************************************************

 What you probably should do is to optimize by Fletcher-Powell (FP)
algorithm which does not require  derivatives.

E-mail : [email-masked]

******************************************************************
From Douglas J. Fox (Director of Technical Support)
******************************************************************

  The limit is on computing the derivatives of integrals using higher
than d functions with ECP's.  This is not an aspect of Gaussian 92 that
was improved with G94.

  You can optimize these geometries with OPT=FP which requires only
energies and not gradients but it can be too slow if you have a large number
of degrees of freedom.

E-mail : [email-masked] 

******************************************************************
******************************************************************

It's therefore clear that it's not possible to compute analytic
derivatives if the basis set of the metal atom describe by an ECP
contains higher than d functions.
The alternative way to optimize a geometry in this case is to use
the FP procedure and thus to choose as small as possible number of 
degrees of freedom.
I thanks all those who answered .
Even those wich are not cited here because they send me MIME encoded
messages wich our mail did not understand.
I hope this sumary will be helpfull.

HUTSCHKA Francois.
Laboratory of Quantum Chemistry
Universite Louis Pasteur
STRASBOURG - FRANCE
E-Mail : [email-masked]

---

From: <[email-masked]>
Date: Thu, 14 Mar 1996 13:22:05 -0500 (EST)

Actually, I've extended the ECP integral routines to higher l(to h? if I 
remeber) values. Actually we have also implemented analytical hessian with 
ECP into Gaussian9x (x=2,4), which might be avaliable in the future. With 
this extension, u can calculate analytical hessian with f function (then of 
course gradient with f function) with DFT, HF, and MP2. (well, f function 
with MP2.., a little disk-demanding)  

However, the issume is, is f function crucial to ur geometry?! I guess 
one should always consider this before doing large calculations. For 
energetics, sure. But for geometry, according to our experince and 
literature, is not not critical. Of course, u know ur system the best. 

Any way, let's hope the code will be released in the near future.

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______________________________________________________________

Qiang Cui
Dept. of Chem. Emory Univ.         508 Webster Dr. Apt.#2
Atlanta, GA 30322.                 Decatur, GA 30033.
(404)-727-2381                     (404)-636-6149

http://tswww.cc.emory.edu/~qcui
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