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      https://www.ias.ac.in/article/fulltext/jcsc/129/10/1611-1626

    • Keywords

       

      Resolution-of-identity; RI; Cholesky decomposition; CD; equation-of-motion; EOM, CC; MP2; electron correlation; excited state; ionization; electron attachment; spinflip; IP; EA; EE; SF.

    • Abstract

       

      We present a Resolution of Identity and Cholesky Decomposition Based Implementation of EOMMP2 approximation. The RI and CD based EOM-MP2 shows significant speed-up and less storage requirement than the conventional canonical version and can be applied to very large systems. The newalgorithm used for this implementation eliminates the most storage requiring four-index quantities resulting in the decrease of storage requirement, reduction in I/O penalties and improved parallel performance, at the expense of more floating point operations. Therefore, the speed-up compared to conventional EOM-MP2 method is more prominent in case of EA, EE and SF case where the storage bottleneck is significant than the EOM-IP-MP2 method, where thestorage requirement is significantly less. However, the RI/CD based EOM-IP-MP2 can be coupled with frozen natural orbitals to gain further speed-up.

    • Author Affiliations

       

      DINESH KUMAR1 ACHINTYA KUMAR DUTTA2 PRASHANT UDAY MANOHAR1

      1. Department of Chemistry, Birla Institute of Technology and Science, Pilani, Rajasthan 333 031, India
      2. Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune, Maharashtra 411 008, India
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