Calculations of bond dissociation energies and dipole moments in energetic materials using density-functional methods.

We compare the effectiveness of six exchange/correlation functional combinations (Becke/Lee, Yang and Parr; Becke-3/Lee, Yang and Parr; Becke/Perdew-Wang 91; Becke-3/Perdew-Wang 91; Becke/Perdew 86; Becke-3/Perdew 86) for computing C-N, O-O and N-NO2 dissociation energies and dipole moments of five compounds. The studied compounds are hexabydro-1,3,5-trinitro-1,3,5-triazine (RDX), dimethylnitramine, cyanogen, nitromethane and ozone. The Becke-3/Perdew 86 in conjunction with 6-31G** is found to give the best results, although for the dipole moments of RDX, there is a slightly difference that B3P86/6-31G** is less reliable than B3P86/6-31+G**.

[Improvement of grating spectrograph and its application to frequency-doubling in PPLN].

Charge-coupled device (CCD) has been widely used in spectral detection and spectral imaging fields, which has a number of benefits: broad spectral range response, low detection limit, wide dynamic range, minimal dark current and readout noise as well as the abilities of signal integration, simultaneous multichannel detection, and real-time detection. The combination of a traditional one meter grating spectrograph and a science charge-coupled device (CCD) led to a real-time grating spectrograph for laser spectrum detection developed in this paper. Based on the new grating spectrograph, the spectral characteristic of frequency-doubling of a broad band double-cladding fiber laser in polarized lithium niobate (PPLN) has been investigated. Dynamic spectrum of the second harmonic with varying temperature of PPLN has been observed and analyzed in detail.