CCL: IR peak in DFT

["Oleg A. Filippov" <H-Bond(~)ineos.ac.ru>]

Dear Friends,
Please don't waste your time with computations of Zn aqua complex, you will NEWER get frequencies in 3000-2000 cm-1 range for this molecule.  The experimental frequencies are could be from counter ion or impurities.

My regards

--
 Dr. Oleg A. Filippov
 A.N. Nesmeyanov Institute of
 Organoelement Compounds, RAS

30.10.2014 15:24, laxmikanth rao lkjoshiji{:}yahoo.com пишет:

Dear Sengupta

As your complex having Zn; perform the geometry optimization using the quasi-relativistic pseudopeotentials of Cu (Hay and Wadt) and a double zeta basis set (lanl2dz) and for other atoms 6-31g(d) basis set.

Taking the optimized geometry(above); do the freq calcns and compare with exptal results

Hope this helps

with regards

Dr J.Laxmikanth Rao

Computational Chemistry,

IICT,Hyderabad  

---

From: Partha Sengupta anapspsmo^^gmail.com <owner-chemistry_+_ccl.net>
To: "Rao, J.laxmikanth " <lkjoshiji_+_yahoo.com>
Sent: Monday, 27 October 2014 12:15 AM
Subject: CCL: IR peak in DFT

Friends,

 I am synthesized a octahedral Zn –water complex (hexa aqua) complex. The Experimental IR spectra shows a number of peaks within the range 3500-300 cm^-.1. One strong intensity peak was observed in 2835, 2461, 2369 and high intensity peak at 2089   cm^-.1..  I perform Density Functional calculation of the same complex with B3LYP/6-31g(d) method with freq keyword.  But I found a gross discrepancy of spectral data in the region 2900- 1900 cm^-1, The computed peak does not show any peak within the range from 3000 cm^-1 10 1750 cm^-1.

Please explain the fact.

Thanking you in advance

Partha S. Sengupta

--
Dr. Partha Sarathi Sengupta
Associate Professor
Vivekananda Mahavidyalaya, Burdwan