CCL:G: clatharte (calc of deltah and deltag; Should I use readisotope option)

 Sent to CCL by: "Gkourmpis, Thomas"
 [Thomas.Gkourmpis^^borealisgroup.com]
 Thakur Hi
 With respect to your second question I would use the freqchk routine and read
 the checkpoint file. The only thing you need is a well optimised structure and
 the relevant checkpoint file. The input line should look something like this
 %chk=mychk
 # Freq=(ReadFC,Temperature=value,Pressure=value) Geom=AllCheck
 This way you can run every combination of pressure and temperature you want.
 I hope this helps
 Thomas
 -----Original Message-----
 > From: owner-chemistry+thomas.gkourmpis==borealisgroup.com(0)ccl.net [mailto:owner-chemistry+thomas.gkourmpis==borealisgroup.com(0)ccl.net] On
 Behalf Of Raj Thakur Veer meandme_meandme2003%x%yahoo.com
 Sent: Saturday, October 02, 2010 7:32 AM
 To: Gkourmpis, Thomas
 Subject: CCL:G: clatharte (calc of deltah and deltag; Should I use readisotope
 option)
 Sent to CCL by: "Raj  Thakur Veer" [meandme_meandme2003!=!yahoo.com]
 Dear CCLers, In a system of clathrate having an entraped guest-gas atom (20
 water molecules and 1 noble gas atom in its cage), is this the way to calculate
 deltaH and deltaG from Gaussian 09 Therochemistry output.
 deltaH= [Eo+Hcorr (of whole system)] - [Eo+Hcorr (of 20 water molec) + Eo+Hcorr
 (of guest atom)]
 Similarly deltaG would be calculated as;
 deltaG= [Eo+Gcorr (of whole system)] - [Eo+Gcorr (of 20 waer molec) + Eo+Gcorr
 (of guest atom)]
 Secondly, in order to calculate thermochemical data at a different temperature
 then default (298.15 k and 1 atm) in gaussian 09, should I use the readisotope
 option in gaussian 09 to use my exp. temp and pressure or I can just use freqchk
 command to extract data at different temp and pressures from checkpoint file I
 have saved from calculations which originally were done at default gaussian temp
 of 298k and 1 atm.for instance, if I want to extract data at 0k, 100k and 150k
 (or else) and 1000 atm. should I use freqchk command in gaussian to extract data
 at this specific temp and pressure or should i rerun gaussian calc and use
 readisotope option to specify my exp. temp and pressure. BUt again, should i
 have to rerun new calc for every temp. and pressure value. I appreciate your
 help.
 ~Titanhttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp-:-//www.ccl.net/chemistry/sub_unsub.shtmlhttp-:-//www.ccl.net/spammers.txt