From owner-chemistry@ccl.net Thu May  8 15:51:00 2014
From: "Mikael Johansson mikael.johansson{=}iki.fi" <owner-chemistry()server.ccl.net>
To: CCL
Subject: CCL: Why is the xc kernel in TD-DFT called a kernel?
Message-Id: <-50054-140508131321-598-8teP1pLOtMmKbNL5aCd0IA()server.ccl.net>
X-Original-From: Mikael Johansson <mikael.johansson#,#iki.fi>
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Date: Thu, 8 May 2014 20:13:11 +0300 (EEST)
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Hola Victor y Todos,

Thanks for that! I obvously need to brush up on my English mathematics :-) 
So kernel is just a very general mathematical term; and here I thought the 
term might contain an interesting story or something...

Anyway, with the right pointers on what to google, came across this page 
with "Earliest Known Uses of Some of the Words of Mathematics", one among 
them, kernel:
   http://jeff560.tripod.com/k.html

Cheers,
     Mikael J.
     http://www.iki.fi/~mpjohans/


On Thu, 8 May 2014, Víctor Luaña Cabal victor*|*fluor.quimica.uniovi.es wrote:

>> Sent to CCL by: Mikael Johansson [mikael.johansson/a\iki.fi]
>>
>> Couldn't contain myself anymore, so here it goes: Why is the kernel, that
>> is, the derivative of the exchange-correlation potential wrt the density,
>>
>>   f_{xc}  =  \delta v_{xc}  /  \delta\rho
>>
>> called the kernel? Where/when was this term coined?

> Mikael,
>
> The Kernel of an integral is not an strange term:
>
> <https://en.wikipedia.org/wiki/Integral_kernel>
>
> Regards,
>        Dr. Víctor Luaña
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