Subject: ECP Second Derivatives?

From: "John Beckerle" <[email-masked]>
Date: 24 Apr 1996 12:46:56 -0500

Subject:                               Time:12:30 PM
  OFFICE MEMO          ECP Second Derivatives?                Date:4/24/96

I am trying to calculate the force constants for a Rhodium carbonyl by DFT
using the LANL2DZ basis set within Gaussian 94.  According to Gaussian, G94
does not have analytic second derivatives for the LANL2DZ basis (with ECP for
Rhodium), so the second derivatives are being numerically evaluated.  This is
taking a long time.  Gaussian is working on analytic second derivatives for
bases with ECPs for the next major release.

I have 3 questions:
1) Is there a rule of thumb for the speed/accuracy differential between
numerical and analytic evaluation of derivatives?

2) Does anyone know of an existing package/software/program for analytic
second derivatives for LANL2DZ with ECPs?

3) Is there another similar/equivalent basis with ECPs for which analytic
second derivatives can be calculated?

4) Any other suggested basis set/theory/package combinations to approach this
problem?

Thanks,
John Beckerle
[email-masked]