Rep:Mod:windows

Laptop in Windows mode

Booting Windows

The default Operating System is Windows. In virtually all regards, operation of the laptop is identical to the desktop machines available to you in the department (and which of course you can also use for this course if you wish). The only significant difference is that the laptop has been partitioned with an E: drive (which desktop systems do not have). This is to enable you to store documents when you are offline, or away from College.

Going online in Windows mode

You can go online with the laptop whilst within the Imperial Chemistry buildings using the wired patch lead used above as part of the initialisation process. If you do want to go online using the Wireless network, see Connection as described here. You should in essence connect to the Imperial-WPA network. IMPORTANT: The default connection settings will not work and you will not go online! When online, this will give you access to all the same drives as any desktop computer would have, including drive H: (your College Windows home drive, where your documents are normally stored), L: (your College Linux home drive, where documents deriving from use of this operating system are normally stored), and Z: (the data silo, where large temporary documents can be stored).

Where you should store your results

If you are working in College, and have the laptop online (via either a wired patch lead or the WiFi), then store everything in the usual place (H:). Alternatively, you will find a drive labelled E:, which is in fact part of the hard drive on the system. You should use this if you are offline, or wish to share a document with Linux. This drive has a total capacity of around 50 Gbytes (compared to 500 Mbyte for drive H:) so you can also use it to store very large files. Be aware however that whilst drive H: is backed up each night, drive E: will not be backed up at all (so if the laptop fails, or is stolen, you will lose everything). We suggest you store your key results on both drives!

How fast is the laptop?

Computational chemistry modelling varies wildly in the amount of computer time need. Thus most molecular mechanics and semi-empirical MO calculations take just seconds, or a minute or so. These are all done on your laptop. The ab initio and DFT procedures can be much more time consuming, and now the issue arises of whether they should even be attempted on your laptop. The particular model you are using is a low-power unit, designed so that the unit is lightweight, and that the battery charge lasts for an entire working day. This means that the processors (of which there are two) are actually relatively slow by modern standards. They are nevertheless fast enough for you to attempt Gaussian calculations on small molecules (typically the size of eg cyclohexane). If you do attempt such a calculation, you will immediately notice that the fans on the laptop kick in very soon, and the unit may get quite hot! For this reason, you should never attempt to run such a calculation for much more than about 1 hour. Under no circumstances should you attempt to leave it running e.g. overnight! If it turns out you do need to run for > 1 hour, then submit to the batch subsystem (SCAN) we have set up for you to use. Not only are the computers you will use there at least 20 times faster than the laptop, such jobs also do not compromise your ability to continue using the laptop, and they also let you run multiple jobs concurrently.