All‐electron all‐virtual spinor space relativistic coupled‐cluster calculations for molecules of heavy elements using contracted basis set: Prediction of atomization energy of PbH 4 *

All‐electron all‐virtual spinor space (AVSS) relativistic second order Møller–Plesset (RMP2), coupled‐cluster singles doubles (RCCSD), RCCSD(T) (RCCSD plus the triple excitation correction included perturbationally) calculations are reported for tetrahedral ( T d ) PbH 4 at various bond lengths using our finite contracted universal Gaussian basis set. Our relativistic calculations predict the RMP2, RCCSD, and RCCD(T) molecular correlation energy for PbH 4 as −2.2563, −2.1917, and −2.2311 au, respectively. Ours are the first AVSS RMP2, RCCSD, and RCCSD(T) molecular calculations for electron correlation energy of the heavy element molecule PbH 4 . All‐electron AVSS coupled‐cluster calculations for the Pb atom are also reported and these were used (in conjunction with the corresponding molecular electron correlation energy calculations for PbH 4 ) to predict atomization energy ( A e ) of PbH 4 at various levels of coupled‐cluster electron correlation. Our predicted atomization energy for PbH 4 (at the optimized bond length of 1.749 Å) with our Dirac–Fock, RMP2, RCCSD, and RCCSD(T) calculations is 5.73, 7.27, 11.24, and 11.62 eV, respectively. Neither such relativistic molecular correlation energy nor atomization energy has been reported so far for heavy polyatomic with 86 electrons. Calculation of relativistic molecular correlation energy is no more a nightmare, and bottlenecks are broken for the calculation of relativistic correlation as well as atomization energy for molecules of heavy elements. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008