**From:** Ramya Gamini (*ramyabhargavi_at_gmail.com*)

**Date:** Wed Jun 10 2009 - 14:01:28 CDT

**Next message:**Àîè: "What decides the pulling direction in SMD?"**Previous message:**Kamilla Kopec: "Force Constant Units"**In reply to:**Kamilla Kopec: "Force Constant Units"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ] [ attachment ]

Hi !

[u cm-2] should mean in units of cm-2

frequency = (1/2*pi) (k/m)^(1/2)

frequency = C (velocity of light) /wavelength (in cm-1)

k is the force constant

m is the reduced mass

k = cm-2* 4*pi^2*C^2*m

[4*pi^2*C^2*m] with 'C' and 'm' in appropriate units should tally the

dimension.

and, may be you have a typo but the other unit should be kcal mol-1 A-2 and

not kcal mol A-2.

hope this helps.

Ramya

On Wed, Jun 10, 2009 at 12:08 PM, Kamilla Kopec <ozero22_at_yahoo.co.uk> wrote:

*> Apologies as this is pretty off-topic
*

*>
*

*> - has anybody come across units of [u cm-2] before for bond stretch force
*

*> constants? I would like to convert a literature force constant quoted in u
*

*> cm-2 to kcal mol A-2 for comparison with one I am using in "charmm22 with
*

*> NAMD". My dimensional analyses have failed to produce a meaningful
*

*> conversion factor - could someone confirm that u cm-2 is a bonafide force
*

*> constant unit?
*

*>
*

*> Many thanks....
*

*>
*

*> Milla
*

*>
*

*>
*

*>
*

*>
*

**Next message:**Àîè: "What decides the pulling direction in SMD?"**Previous message:**Kamilla Kopec: "Force Constant Units"**In reply to:**Kamilla Kopec: "Force Constant Units"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ] [ attachment ]

*
This archive was generated by hypermail 2.1.6
: Wed Feb 29 2012 - 15:51:05 CST
*