Subject: energy of a singlet state in which HOMO wavefunction is substituted by LUMO wavefunction

From: "Kiniu WONG Kin-Yiu" <[email-masked]>
Date: Fri, 17 Nov 2000 02:26:34 +0800

Dear all,

    I want to find the excitation energy from a singlet ground state to
another singlet state (excited).  I know CIS in Gaussian is able to
calculate it, however, the disk space of the CIS computation required for
our molecule (Alq3) exceeds the upper limit (~25GB) of Gaussian.  Therefore,
instead of calculating a whole CI with a number of Slater determinants, I
want to find out the energy of a singlet state in which HOMO wavefunction is
substituted by LUMO wavefunction, and treat it as the energy of the first
excited state.  But I don't know how to use Gaussian to compute it, can
anybody teach me?  Thank you in advance!

Wishes,
Kiniu

----
Kiniu WONG Kin-Yiu
Undergraduate student
Department of Physics
The Chinese University of Hong Kong
Email: [email-masked]  or  [email-masked]

---

From: "Phillip D. Matz" <[email-masked]>
Date: Thu, 16 Nov 2000 11:48:01 -0800

Hello Kiniu,

> our molecule (Alq3) exceeds the upper limit (~25GB) of Gaussian.
Therefore

If you still want to use CIS then you can specify CIS(Direct) and then you
will find that the calculation will proceed correctly.

Respectfully,
Phillip Matz
[email-masked]

----- Original Message -----
From: "Kiniu WONG Kin-Yiu" <[email-masked]>
To: <[email-masked]>
Sent: Thursday, November 16, 2000 10:26 AM
Subject: CCL:energy of a singlet state in which HOMO wavefunction is
substituted by LUMO wavefunction

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