Subject: Shallow minimum

From: "R.B.Sunoj" <[email-masked]>
Date: Wed, 7 Mar 2001 10:58:23 +0530 (IST)

Dear Netters,

If there is a possibility of two minima on the PES which lie close to each
other and one of them is very shallow, how one can find this shallow
minimum?.

In Gaussian scf=(tight,qc) will be of help?

Thanks in advance,

Sunoj

---

From: Herbert Fruchtl <[email-masked]>
Date: Wed, 07 Mar 2001 10:41:23 +0000

> other and one of them is very shallow, how one can find this shallow

Generally, if you want to stay in a metastable minimum with low barrier:

- Make sure you start close to the minimum you're searching.
- If at all possible, get a good starting Hessian. If you use a lower 
level of theory for this, make sure that the minimum exists on this level.
- Restrict the step size.

> In Gaussian scf=(tight,qc) will be of help?
You might have to make it tight. The convergence method (qc or otherwise)
shouldn't matter (as long as it converges at all).

HTH,

  Herbert
-- 
******************************************************
* Herbert Fruchtl        Tel.: +44-(0)20-8606-4650   *
* FECIT                  Fax:  +44-(0)20-8606-4422   *
* 2 Longwalk Road        email: [email-masked] *
* Stockley Park                                      *
* Uxbridge UB11 1AB, United Kingdom                  *
******************************************************