With the successful demonstration of the use of negative phase velocity materials (NPVMs) for making super lenses with resolution capabilities not limited by the conventional diffraction limit, a considerable amount of interest has been shown in using subwavelength structures to develop materials having qualitatively new response functions not occurring in nature. These materials result in modified Snell’s law of refraction, a reversed Doppler shift and an obtuse angle for Cerenkov radiation [see e.g. Veselago, V.G., Sov. Phys. Usp. 10 (1968) 509-514]. The perfect lens enables imaging with subwavelength resolution, and has attracted the attention of many researchers in studying its focusing and imaging characteristics. With the universal acceptance of the phenomenon of negative refraction (NR) and the suitability of some photonic crystals (PhCs) as left-handed materials (LHMs), considerable interest has also been shown in studying the PhCs in the context of NR. In less than a decade, many interesting investigations on the basis of materials with NR, e.g. superlens designing, focusing, resolution, defect modes, resonance modes, anomalous effects, and nonlinear effects etc. have been reported. These materials are becoming increasingly important for fabricating some devices in the fields of Photonics and Microwave Technologies. This review is an attempt to present a glimpse of publications in the year 2007, of the rapidly growing field which has now become so vast that it is nearly impossible to cover everything. No claim is made as to the completeness of the reporting of various investigations on the subject. Such surveys for the years 2005, 2006, and 2008 have already been published (1-4).

1. K.N.Chopra, Joby Joseph and Kehar Singh, Invertis J. Sci. Technol. 3 (2010)

2. K.N. Chopra, Sanjay Kumar, Joby Joseph and Kehar Singh, Invertis J. Sci. Technol. 4 (2011) 84-126.

3. K.N. Chopra, Sanjay Kumar, Joby Joseph and Kehar Singh, Invertis J. Sci. Technol. 4 (2011) 146-187.

4. K.N. Chopra, Joby Joseph and Kehar Singh, Asian J. Phys. 18 (2009) 17-56.

 Vol. 20, No. 4 (2011) 403-423

3. Density functional theory computations on vibrational spectra:

Scaling procedures to improve the results

M Alcolea Palafox^a and V K Rastogi^b

^aDepartamento de Química-Física I. Facultad de Ciencias Químicas Universidad
Complutense, Madrid- 28040-ES. SPAIN

^bDepartment of Physics, CCS University Campus, Meerut-250004, India.

The basic Density Functional Theory (DFT) was described, and the most common density functionals were listed. The performance of ab initio and DFT methods in calculating the geometric parameters and vibrational frequencies was analyzed. The accuracy of the results in the isolated state, as well as in the solid state was shown in the IR and Raman spectra. To correct the calculated frequencies, several scaling procedures were described in detail. A comprehensive compendium of the mainly scale factors available to date for a good accurate prediction of the frequencies was also shown. Examples of each case were presented, with special attention to the benzene and uracil molecules and to some of their derivatives.