ChemOffice.Com - CambridgeSoft

Chapter 11:
Computations
Gaussian Overview
The following procedures describe the graphical
user interface (GUI) Chem3D provides for users of
Gaussian 03W. For information about how to use
Gaussian, see the documentation supplied by
Gaussian, Inc., makers of the application.
Gaussian 03W is not included with Chem3D, but
can be purchased separately from CambridgeSoft.
You can use the Online menu command Browse
ChemStore.com to link directly to the website.
Gaussian 03
Gaussian 03W is a powerful computational
chemistry application including both ab initio and
semiempirical methods. Gaussian is a
command-line application that requires a user to
type text-based commands and data instead of
selecting graphical objects and menu items.
Chem3D serves as a front-end GUI for
Gaussian 03W, enabling you to create and run
Gaussian jobs in Chem3D. The model in the
Chem3D window transparently provides the data
for Gaussian computations. Menus and dialog
boxes replace the many Gaussian commands,
although Chem3D preserves the option to use
them for less common and advanced computations.
Minimize Energy
To perform a minimize energy computation on a
molecule:
From the Calculations menu, point to Gaussian and
choose Minimize Energy.
Gaussian
The Minimize Energy dialog box appears.
The Job Type Tab
The Job Type tab of the dialog box defaults to
Minimize Energy when you select Minimize Energy
from the menu. Job Type can be changed to
Compute Properties from within this tab.
Select the appropriate options:
If you want to …
watch the minimization
process “live” at each
iteration in the
calculation
Then select …
Display Every Iteration
NOTE: Displaying or
recording each iteration adds
significantly to the time
required to minimize the
structure.
ChemOffice 2005/Chem3D Gaussian Computations • 195
Gaussian 03