USE OF NEGATIVE COMPLEX POTENTIAL AS ABSORBING POTENTIAL

Exact numerical calculation shows that the use of negative complex pot ential (NCP) significantly improves the efficiency of wavefunction abs orption over that of negative imaginary potential (NIP) in scattering applications. The improvement in absorption is especially significant in the case of low energy scattering with de Broglie wavelength larger than the length of absorbing potential. The addition of a negative re al potential to the pure imaginary potential speeds up the absorption of wavefunction by effectively shortening its de Broglie wavelength. E xplicit TD numerical calculation for a one-dimensional model demonstra tes the effectiveness of the NCP and shows that the reflection from th e absorbing potential can effectively be eliminated by using optimized absorbing parameters for the energy in question. In addition, compari son of the exact numerical calculation with semiclassical WKB analysis casts a serious doubt an the quantitative value of using WKB analysis at low energies with de Broglie wavelengths much larger than the abso rbing length and/or for polynomial absorbing potentials higher than li near. (C) 1998 American Institute of Physics. [S0021-9606(98)01004-6].