RESUMO
We present here a set of algorithms that completely rewrites the Hartree-Fock (HF) computations common to many legacy electronic structure packages (such as GAMESS-US, GAMESS-UK, and NWChem) into a massively parallel compute scheme that takes advantage of hardware accelerators such as Graphical Processing Units (GPUs). The HF compute algorithm is core to a library of routines that we name the Quantum Supercharger Library (QSL). We briefly evaluate the QSL's performance and report that it accelerates a HF 6-31G Self-Consistent Field (SCF) computation by up to 20 times for medium sized molecules (such as a buckyball) when compared with mature Central Processing Unit algorithms available in the legacy codes in regular use by researchers. It achieves this acceleration by massive parallelization of the one- and two-electron integrals and optimization of the SCF and Direct Inversion in the Iterative Subspace routines through the use of GPU linear algebra libraries. © 2015 Wiley Periodicals, Inc.
Assuntos
Algoritmos , Computadores , Gráficos por Computador , Elétrons , Teoria Quântica , SoftwareRESUMO
This article describes an extension of the quantum supercharger library (QSL) to perform quantum mechanical (QM) gradient and optimization calculations as well as hybrid QM and molecular mechanical (QM/MM) molecular dynamics simulations. The integral derivatives are, after the two-electron integrals, the most computationally expensive part of the aforementioned calculations/simulations. Algorithms are presented for accelerating the one- and two-electron integral derivatives on a graphical processing unit (GPU). It is shown that a Hartree-Fock ab initio gradient calculation is up to 9.3X faster on a single GPU compared with a single central processing unit running an optimized serial version of GAMESS-UK, which uses the efficient Schlegel method for s- and l-orbitals. Benchmark QM and QM/MM molecular dynamics simulations are performed on cellobiose in vacuo and in a 39 Å water sphere (45 QM atoms and 24843 point charges, respectively) using the 6-31G basis set. The QSL can perform 9.7 ps/day of ab initio QM dynamics and 6.4 ps/day of QM/MM dynamics on a single GPU in full double precision. © 2015 Wiley Periodicals, Inc.
RESUMO
The mol-ecular structure of the title compound, C(22)H(34)N(3)OP, adopts a distorted tetra-hedral geometry at the P atom, with the most noticeable distortion being for the O-P-N angle [117.53â (10)°]. An effective cone angle of 187° was calculated for the compound. In the crystal, weak C-Hâ¯O inter-actions create infinite chains along [100], whereas C-Hâ¯π inter-actions propagating in [001] generate a herringbone motif.
RESUMO
In the title compound, C(30)H(48)BNOP(2)·0.5H(2)O, the water molecule is disordered about an inversion centre. Both phospho-rus atoms shows distortions in their tetra-hedral environments with the cyclo-hexyl substituents disordered over two orientations in a 0.851â (3):0.149â (3) occupancy ratio. The crystal structure is assembled via O-Hâ¯O inter-actions between pairs of phosphininc amide mol-ecules and water molecules, creating hydrogen-bonded dimers with graph-set R(2) (4)(8) along [001]. Weak C-Hâ¯O inter-actions are also observed.