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University of Alaska Fairbanks
Department of Chemistry and Biochemistry

Updated 3-7-2019

A Pi molecular orbital of PABA, and hyperlink to login page
To login, click this graphic.

This site provides quick access to the MOPAC semi-empirical quantum mechanics program via WebMO, a graphical web-based interface for constructing molecular models, carrying out calculations, and viewing calculation results. Please note: the main departmental server for research and advanced educational use is at another site: that one runs Gaussian09 which offers a variety of ab initio and density functional theory methods.
Login. Start by clicking the MO graphic at the top of this page. The standard login is as "guest", password "webmo". However, if another username has been assigned to your class or lab section, please use it, not the guest account. Chem 105 jobs are limited to 10 min but they should finish in seconds.
Alternate WebMO server. If for some reason the UAF chem dept WebMO servers are down or unreachable, the "Working Demo" website at Hope College, MI, can run MOPAC calculations. 


Login as guest, pwd guest. Be sure to include an identifier in the job name, otherwise it may be difficult to find your output, since jobs are being submitted continuously from around the world (the job number currently is at 490,000). Jobs on this server are limited to 1 min.

YouTube videos illustrating Experiment 5 :
   Parts I and II. Lewis formula. Testing VSEPR geometry prediction
   Part IV. Investigating resonance formulas
   Part V. Displaying p and s molecular orbitals

VSEPR geometry table PDF

Web-Based Molecular Modeling.  Links to several web pages showing Lewis formulas, rotatable molecules, atomic and molecular orbitals, and electrostatic potential surfaces.


Server Physical Cores Threads (="cores") Memory (GB) Processor Gaussian NWChem MOPAC
Obsidian 6 12 32 Core i7 5930K a a a
Chemlinux1 8 8 16 Xeon a a a
Corsair3 10 20 64 Core i7 6950X a a a
Antec12 6 12 32 Core i7 5820K a a a
Rosewill 24 24 64 Zen 2970wx a a a


In the table above, servers are listed in the "First Available" order. If you do not choose a specific server under "Select Server,"  your job is assigned in this order starting at the top of the list. The default number of cores, i.e. threads, assigned per job is 4, unless you specify more on the Advanced tab. (The hyperthreading feature of Intel chips doubles the number of cores visible to the operating system. Thus the "Cores" box in WebMO actually refers to threads.) WebMO will run two simultaneous "6-core" jobs on Obsidian, say, before assigning a job to the next server, Chemlinux1. To request the maximum number of threads on a given machine, choose the server under the Select Server pull-down menu. Under the Advanced tab, set the number of cores (i.e. threads) equal to the number in column 3.

For more information, see following links:
WebMO  https://www.webmo.net
MOPAC  http://openmopac.net
Gaussian https://www.gaussian.com
Contact: jwkeller /at/ alaska.edu