11 February 2002 Physics Letters A 294 (2002) 52–57 www.elsevier.com/locate/pla Application of Mathieu potential to photoemission calculations: the case of a strong potential Zaithanzauva Pachuau a , B. Zoliana a , P.K. Patra c , D.T. Khating b , R.K. Thapa c,∗ a Department of Physics, Government Zirtiri Residential Science College, Aizawl 796 001, Mizoram, India b Department of Physics, North-Eastern Hill University, Shillong 793 022, India c Condensed Matter Theory Research Group, Department of Physics, Pachhunga University College, Mizoram University, Aizawl 796 001, Mizoram, India Received 29 August 2001; accepted 18 December 2001 Communicated by J. Flouquet Abstract We have applied the Mathieu potential model to photoemission calculations from metals. The case of a strong potential is considered to describe the wavefunctions which is used for the evaluation of photocurrent from tungsten, molybdenum, copper and silicon.  2002 Published by Elsevier Science B.V. PACS: 73.20; 79.60 Keywords: Photoemission; Photocurrent; Wavefunction; Surface; Dielectric function 1. Introduction We report here a simple formalism developed for photoemission studies by using the Mathieu potential to describe the bulk and the surface regions of metals. This case had been already reported [1] but in the case of aluminium and beryllium. Though the photocurrent data in these metals showed good behaviour conform- ing to some extent to the theoretical and experimen- tal results published earlier, however, the nearly empty potential model (q ∼ 0) had its own limitations. For example, it could be applied only to the free electron * Corresponding author. E-mail address: ramkumar_thapa@yahoo.com (R.K. Thapa). type of metals. In order that the model could be ex- tended to the case of metals which has strong poten- tials (q> 0), one can therefore make use of Mathieu potential model to strong and finite type of potentials to deduce the wavefunctions for the bulk and surface regions. Wavefunctions so deduced can be then used to calculate the photocurrent by evaluating the matrix element as a function of photon energy and surface width. Mathieu potential has been used at first by Statz [2] for surface state calculations. Levine [3] had also used the Mathieu potential for calculating the conditions for arbitrary surface terminations. We have used in this formalism the model as described by Davison and Steslicka [4], as shown in Fig. 1. The simplest way to represent a periodic potential in a one-dimensional 0375-9601/02/$ – see front matter  2002 Published by Elsevier Science B.V. PII:S0375-9601(01)00856-8