Passing the several billions limit in FCI calculations on a mini-computer

✍ Scribed by Alexander O. Mitrushenkov

• Book ID: 103032830
• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 598 KB
• Volume: 217
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(93)e1425-g

✦ Synopsis

An efficient realization of a determinant-based algorithm for the large full configuration interaction (FCI) problem is presented, it effectively exploits the sparsity of the CI vector. Within this technique we reproduced the one billion calculation for the 'S ground state of the Mg atom on a Spare IPC minicomputer to an uncertainty of lo-' hartree within a threshold of lo-' for the CI vector. Calculations are also performed for the 'P excited state of Mg. As an example, which is at the limit of the hardware available on our computer, the ground state of the Hz0 molecule in the [ 5s3pld/3slp] AN0 basis set is calculated. The FCI expansion of the ground state vector yields over 7.2 billion Czv determinants. A ground state energy of -76.305 hartree with an estimated accuracy of 2 x 1 O-) hartree in this basis set is obtained within the total time of 170 h. One iteration of the CI vector in this basis set with a threshold of 10e5 is performed in 100 Mbyte disk space and took 4200 min of the total computation time.