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##

Brief Description

The spin-restricted open-shell Hartree-Fock method (ROHF) can always
be chosen to systems where all unpaired spins are parallel. The
`TURBOMOLE` keywords for such a case (one open shell, triplet
e) are:

$open shells type=1
eg 1 (1)
$roothaan 1
a=1 b=2

It can also treat more complicated open-shell cases, as indicated in
the tables below. In particular, it is possible to calculate the
[xy]
case. As a guide for expert users,
complete ROHF `TURBOMOLE` input for O for various CSFs
(configuration state function) is given in Section 15.6.
Further examples are collected below.

The ROHF ansatz for the energy expectation value has a term for
interactions of closed-shells with closed-shells (indices ), a
term for purely open-shell interactions (indices ) and a coupling
term ():

where is the (fractional) occupation number of the open-shell part
(), and and are the Roothaan parameters, numerical
constants which depend on the particular configuration of interest.

** Next:** One Open Shell
** Up:** Restricted Open-Shell Hartree-Fock
** Previous:** Restricted Open-Shell Hartree-Fock
** Contents**
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TURBOMOLE