title: Challenges in first-principles NPT molecular dynamics of soft porous crystals: a case study on MIL-53(Ga).
abstract: Soft porous crystals present a challenge to molecular dynamics simulations with flexible size and shape of the simulation cell (i.e., in the NPT ensemble), since their framework responds very sensitively to small external stimuli. Hence, all interactions have to be described very accurately in order to obtain correct equilibrium structures. Here, we report a methodological study on the nanoporous metal-organic framework MIL-53(Ga), which undergoes a large-amplitude transition between a narrow- and a large-pore phase upon a change in temperature. Since this system has not been investigated by density functional theory (DFT)-based NPT simulations so far, we carefully check the convergence of the stress tensor with respect to computational parameters. Furthermore, we demonstrate the importance of dispersion interactions and test two different ways of incorporating them into the DFT framework. As a result, we propose two computational schemes which describe accurately the narrow- and the large-pore phase of the material, respectively. These schemes can be used in future work on the delicate interplay between adsorption in the nanopores and structural flexibility of the host material.
authors.affiliation: Ecole Normale Supérieure-PSL Research University, Département de Chimie, Sorbonne Universités - UPMC Univ Paris 06, CNRS UMR 8640 PASTEUR, 24, rue Lhomond, 75005 Paris, France.
authors.forename: Volker
authors.initials: V
authors.lastname: Haigis
authors.affiliation: Ecole Normale Supérieure-PSL Research University, Département de Chimie, Sorbonne Universités - UPMC Univ Paris 06, CNRS UMR 8640 PASTEUR, 24, rue Lhomond, 75005 Paris, France.
authors.forename: Yacine
authors.initials: Y
authors.lastname: Belkhodja
authors.affiliation: PSL Research University, Chimie ParisTech - CNRS, Institut de Recherche de Chimie Paris, 75005 Paris, France.
authors.forename: François-Xavier
authors.initials: FX
authors.lastname: Coudert
authors.affiliation: Ecole Normale Supérieure-PSL Research University, Département de Chimie, Sorbonne Universités - UPMC Univ Paris 06, CNRS UMR 8640 PASTEUR, 24, rue Lhomond, 75005 Paris, France.
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Vuilleumier
authors.affiliation: Ecole Normale Supérieure-PSL Research University, Département de Chimie, Sorbonne Universités - UPMC Univ Paris 06, CNRS UMR 8640 PASTEUR, 24, rue Lhomond, 75005 Paris, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Boutin