Ab initio structural study of the B₄H₄ molecule. Asymmetric structure for a `symmetric' system

Pavel Mach^a, Ivan Huba^a and Aristides Mavridis<sup>b

a</sup> Department of Biophysics and Molecular Physics, Faculty of Mathematics and Physics, Comenius University, 84215 Bratislava, Slovak Republic
^b Laboratory of Physical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistemiopolis, Athens 157 71, Greece

Received 1 April 1994;  revised 3 June 1994.  Available online 28 November 2001.

Abstract

Ab initio calculations on the B₄H₄ molecule using MP2, MP4, and CISD methodologies, reveal that the ground state of this system has a (planar) C_s instead of the highly symmetric T_d structure, the energy difference being approximately 6 kcal/mol. An attempt is made to rationalise this finding by invoking the excited a ³ state of the B-H unit.