Supplementary Material
Table A. The coordinates (in ?) of H2Sn, n = 1-9, derived after optimization of the structure, using
the MNDO method (model 3).
Figure A. Variation of γxxyy, γxxzz, γyyzz and γ as a function of n (H2Sn), for models 1, 2 and 3. On the
left vertical axis the γxxyy, γxxzz and γyyzz are given, while on the right the average value γ is
presented. This option has been used because the cross terms and the average values have
different scales of variation. The average value is shown in this Figure in order to facilitate
the comparison between the diagonal terms presented in Figure 8 (where the average
values are also shown).