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Semiempirical Self-Consistent Polarization Description of Bulk Water, the Liquid-Vapor Interface, and Cubic Ice

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Semiempirical Self-Consistent Polarization Description of Bulk Water, the Liquid-Vapor Interface, and Cubic Ice http://www.ncbi.nlm.nih.gov/pubmed/21370904. Postprint available at: http://www.zora.uzh.ch Zurich Open Repository and Archive University of Zurich Posted at the Zurich Open Repository and Archive, University of Zurich. Main Library http://www.zora.uzh.ch Winterthurerstr. 190 CH-8057 Zurich www.zora.uzh.ch Originally published at: Murdachaew, G; Mundy, C J; Schenter, G K; Laino, T; Hutter, J (2011). Semiempirical self-consistent polarization description of bulk water, the liquid-vapor interface, and cubic ice. Journal of Physical Chemistry. A, 115(23):6046-6053. Year: 2011 Semiempirical self-consistent polarization description of bulk water, the liquid-vapor interface, and cubic ice Murdachaew, G; Mundy, C J; Schenter, G K; Laino, T; Hutter, J http://www.ncbi.nlm.nih.gov/pubmed/21370904. Postprint available at: http://www.zora.uzh.ch Posted at the Zurich Open Repository and Archive, University of Zurich. http://www.zora.uzh.ch Originally published at: Murdachaew, G; Mundy, C J; Schenter, G K; Laino, T; Hutter, J (2011). Semiempirical self-consistent polarization description of bulk water, the liquid-vapor interface, and cubic ice. Journal of Physical Chemistry. A, 115(23):6046-6053. Semiempirical self-consistent polarization description of bulk water, the liquid-vapor interface, and cubic ice Abstract We have applied an efficient electronic structure approach, the semiempirical self-consistent polarization neglect of diatomic differential overlap (SCP-NDDO) method, previously parametrized to reproduce properties of water clusters by Chang, Schenter, and Garrett J. Chem. Phys. 2008, 128, 164111] and now implemented in the CP2K package, to model ambient liquid water at 300 K (both the bulk and the liquid-vapor interface) and cubic ice at 15 and 250 K The SCP-NDDO potential retains its transferability and good performance across the full range of conditions encountered in the clusters and the bulk phases of water. In particular, we obtain good results for the density, radial distribution functions, enthalpy of vaporization, self-diffusion coefficient, molecular dipole moment distribution, and hydrogen bond populations, in comparison to experimental measurements. Semiempirical Self-Consistent Polarization Description of Bulk Water, the Liquid-Vapor Interface, and Cubic Ice Garold Murdachaew (Email: [email protected]), Christopher J. Mundy (Corresponding author; Email: [email protected], Phone: +1 509-375-2404, Fax: +1-509-375-2644), and Gregory K. Schenter (Email: [email protected]) Chemical & Materials Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA Teodoro Laino (Email: [email protected]) Physical Chemistry Institute, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland and IBM Zurich Research Laboratory, S¨aumerstrasse 4, CH-8803 R¨uschlikon,Switzerland J¨urgHutter (Email: [email protected]) Physical Chemistry Institute, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland (Dated: January 25, 2011) 1 Abstract We have applied an efficient electronic structure approach, the semiempirical self-consistent po- larization neglect of diatomic differential overlap (SCP-NDDO) method, previously parametrized to reproduce properties of water clusters by Chang, Schenter, and Garrett [J. Chem. Phys. 128, 164111 (2008)], and now implemented in the CP2K package, to model ambient liquid water at 300 K (both the bulk and the liquid-vapor interface) and cubic ice at 15 K and 250 K. The SCP-NDDO potential retains its transferability and good performance across the full range of conditions en- countered in the clusters and the bulk phases of water. In particular, we obtain good results for the density, radial distribution functions, enthalpy of vaporization, self-diffusion coefficient, molec- ular dipole moment distribution, and hydrogen-bond populations, in comparison to experimental measurements. 2 1. INTRODUCTION Despite large improvements in the algorithms of ab initio methods and advances in soft- ware and hardware, there will continue to exist system sizes and time durations for which the scaling of ab initio methods like CCSD(T), MP2, and even DFT remain prohibitive.1 Our own interest is in modeling the molecular condensed phase using molecular dynamics simulations, both with classical and quantum treatment of the nuclei. Since we would like to accurately describe many-body polarization effects, and, eventually, the breaking and forma- tion of chemical bonds, effective two-body classical potentials will not suffice, and we have to use a method that will faithfully describe the electronic structure during the course of the simulation. Most such direct dynamics or first-principles simulations2,3 have been performed using Kohn-Sham density-functional theory (DFT)4,5, a method that is efficient enough to sample the configurational space, at least for some applications. Semiempirical (SE) methods have a long history in computational quantum chemistry. One class of these methods was originally developed to reduce the cost of the Hartree-Fock molecular orbital method, and, through parametrization, to include some of the missing cor- relation effects. The modern version of this approximation is based on neglect of diatomic differential overlap (NDDO).6,7 Some widely used parametrizations have been the MNDO,8 AM1,9 PM3,10,11 and PM612 approaches. The other class of SE methods is the tight- binding approximation to DFT, for example the self-consistent-charge density-functional tight-binding (SCC-DFTB)13 method. SE methods are less costly than DFT. Therefore, they may enable more extensive sampling during a simulation. Both NDDO-based and DFTB-based SE methods have been an effective and efficient approach for chemically-bonded complexes. Some deficiencies of DFT are the lack of the dispersion interaction and an often poor description of weakly-bound systems.14 Thus, new exchange-correlation functionals15,16 and empirical dispersion corrections17,18 have been developed for DFT. Similar corrections have also been applied to the NDDO-based19,20 and to the DFTB-based21,22 SE methods. A gen- eral conclusion is that no purely ab initio method exists for an on-the-fly electronic structure 3 description that is both efficient and accurate. The two currently feasible approaches, DFT and SE (either NDDO or DFTB) both require some degree of tuning to accurate experimen- tal or ab initio data. Here we will focus on the NDDO-based SE methods. There have been many attempts to improve the NDDO methods' description of the hydrogen bond. A pairwise core re- pulsion function was added to MNDO in the MNDO/H,23 MNDO/GH,24 MNDO/M,25,26 and I-MNDO27 methods. After MNDO, the newer AM1,9 PM3,10 and PM612 parametriza- tions were introduced. To improve the description of hydrogen bonds, additional empirical functions where added in the (AM1,PM3)-PIF,19 PM3-MAIS,20 and PDDG-(MNDO,PM3)28 methods. A different definition of the electron integrals was used in the SAM1 method.29 Additional basis functions of p symmetry were added to H atoms in the SINDO/130 method. Orthogonalization corrections were introduced in the OMn31,32 methods. As mentioned, post-SCF dispersion corrections1,33 have also been added. The NDDO-based SE methods have been used to model the condensed phase (see, e.g., refs 34{38), as have the DFTB-based SE methods. For simulations of ambient water, see, e.g., refs 21,22,38. In ref 39 some of us introduced a different correction approach. The self-consistent po- larization (SCP) approach uses an auxiliary charge density (modeled by one or at most a few Gaussian centers placed on atomic sites) which supplements the NDDO or DFT charge densities and is used to better describe the intermolecular interaction. SCP-NDDO was de- veloped first and used to correct the deficiencies of the PM3 description of water clusters39 (geometries, binding energies, and harmonic frequencies). Later, the same SCP approach was used to correct the deficiencies of the BLYP DFT functional in describing argon clus- ters40 and water clusters.41 The SCP-NDDO and SCP-DFT approaches were parametrized on properties of clusters and used to predict other cluster properties and, in a successful test of transferability, bulk properties, in good agreement with accurate theoretical and experi- mental benchmarks (SCP-DFT for liquid and solid argon40: radial distribution functions or RDFs and cohesion energy curves; SCP-DFT for liquid ambient water:41 RDFs and enthalpy of vaporization). 4 In this work, we present the SCP-NDDO predictions for bulk water. Water in the liquid, interfacial, and solid states has been of interest to many fields and ambient liquid water in particular has been studied computationally for decades with a variety of potentials.42 An efficient and accurate description which includes the electronic state would be of interest to many fields including biology43 and catalysis and atmospheric science.44 In this work we present our SCP-NDDO results for ambient bulk and interfacial water and also for cubic ice, as obtained from SE molecular dynamics simulations. 2. IMPLEMENTATION OF NDDO AND SCP-NDDO FOR EXTENDED SYS- TEMS 2.1. Overview of SCP-NDDO theory The SCP-NDDO method was fully described in ref 39. Some essential points are summa- rized here. The SCP-NDDO total energy is given by E = Eself + Ecoul + Eex + Ecore + Edisp; (1) where the respective terms' subscripts refer to the self, Coulomb, resonance+exchange, core, and dispersion contributions. The self and Coulomb terms have SCP contributions which differentiate the SCP-NDDO method from the parent MNDO and PM3 methods. Many of the parameters have been re-fitted39 and thus differ slightly from their original values.10 In addition, the screening function (and thus the integrals) in the terms differ from those in the parent methods. Diagonalization of the associated Fock matrix yields the self-consistent problem which is solved variationally for the electron and polarization density matrices. The dispersion term is an additional, post-SCF (i.e., post-processed) term.
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