Electron density has the same units as f/V, i.e. Angstroem^-3 (and of course dimensions L^-3). Again if you insist, you can have units 'e*Angstroem^-3' as long as you define somewhere the dimensionless scale factor 'e'=1, but again it doesn't get you anywhere. One should avoid attempting to infer definitions of quantities from their names, sometimes it works & sometimes it doesn't: what matters is the formal definition, in this case electron density is defined as 'number of electrons per unit volume'. Again 'number of electrons' is just a pure number just like 'number of apples' (I'm assuming that 'number' here is not restricted to integers): it has nothing to do with the concept of 'electron' (or 'apple'), except insofar that electrons and apples are concepts to which the operation of counting can meaningfully be applied.
I. > -----Original Message----- > From: owner-ccp...@jiscmail.ac.uk > [mailto:owner-ccp...@jiscmail.ac.uk] On Behalf Of Bernhard Rupp > Sent: 26 February 2010 18:39 > To: Ian Tickle; CCP4BB@JISCMAIL.AC.UK > Subject: RE: [ccp4bb] units of f0, f', f'' > > <NOTATION> > Notation > ======== > > f0: atomic scattering factor for normal scattering, defined > as the ratio > of scattered amplitude to that for a free electron. > </NOTATION> > > ---------------------------------------------------------------------- > Hmmm...where does the 'electron' in electron density then > come from after > integration/summation over the structure factors? > ---------------------------------------------------------------------- > > BR > > Disclaimer This communication is confidential and may contain privileged information intended solely for the named addressee(s). It may not be used or disclosed except for the purpose for which it has been sent. If you are not the intended recipient you must not review, use, disclose, copy, distribute or take any action in reliance upon it. If you have received this communication in error, please notify Astex Therapeutics Ltd by emailing i.tic...@astex-therapeutics.com and destroy all copies of the message and any attached documents. Astex Therapeutics Ltd monitors, controls and protects all its messaging traffic in compliance with its corporate email policy. The Company accepts no liability or responsibility for any onward transmission or use of emails and attachments having left the Astex Therapeutics domain. Unless expressly stated, opinions in this message are those of the individual sender and not of Astex Therapeutics Ltd. The recipient should check this email and any attachments for the presence of computer viruses. Astex Therapeutics Ltd accepts no liability for damage caused by any virus transmitted by this email. E-mail is susceptible to data corruption, interception, unauthorized amendment, and tampering, Astex Therapeutics Ltd only send and receive e-mails on the basis that the Company is not liable for any such alteration or any consequences thereof. Astex Therapeutics Ltd., Registered in England at 436 Cambridge Science Park, Cambridge CB4 0QA under number 3751674
