From NWChem
Viewed 2004 times, With a total of 0 Posts

Clicked A Few Times
Threads 10
Posts 24


9:19:25 PM PDT  Sat, May 23rd 2015 

Quibble:
In ./src/vib/vib_wrtfreq.F,
truncated and rounded off constants are applied in
each loop iteration of the ZPE, thermal enthalpy and
energy calculation. The roundoff error accumulation
reaches the milliHartree level for small molecules (e.g.,NH3)
is more than I'd like.
I suggest a modest correction.
According to NIST's CODATA 2011 docs
at http://physics.nist.gov/cuu/Constants/index.html ,
these constants are welldefined.
Speed of Light = 299792458 m/s = 2.99792458e+10 m/s
Planck's constant = 6.62606957e34 Jsec = 6.62606957e27 ergsec
Boltzmann constant = 1.3806488e23 J/K = 1.3806488e16 ergK
Ideal Gas Constant = 8.3144621 J/molK = 1.9872041 cal/molK
In the May 4 development version
Nwchemdev.revision27039src.20150504/src/vib/vib_wrtfreq.F
lines 42,43 are:
parameter (c=2.998e+10,h=6.626e27,kgas=1.3807e16) ! cgs units
parameter (Rgas = 1.9863d0/1000.0d0/AUKCAL) ! atomic units
They may be revised to read:
parameter (c=2.99792458e+10,
& h=6.62606957e27,
& kgas=1.3806488e16) ! cgs units
parameter (Rgas = 1.9872041d0/1000.0d0/AUKCAL) ! atomic units
Thanks,
drh

Edited On 7:21:54 AM PDT  Sun, May 24th 2015 by Drhaney



AWC's:
2.5.10 MediaWiki  Stand Alone Forum Extension
Forum theme style by: AWC