Low-pressure phase diagram of crystalline benzene from quantum Monte Carlo

Abstract

We study the low-pressure (0 to 10 GPa) phase diagram of crystalline benzene using quantum Monte Carlo (QMC) and density functional theory (DFT) methods. We consider the $Pbca$, $P{4}_3{2}_{1}2$, and $P{2}_1/c$ structures as the best candidates for phase I and phase II. We perform diffusion quantum Monte Carlo (DMC) calculations to obtain accurate static phase diagrams as benchmarks for modern van der Waals density functionals. We use density functional perturbation theory to compute phonon contribution in the free-energy calculations. Our DFT enthalpy-pressure phase diagram indicates that the $Pbca$ and $P{2}_1/c$ structures are the most stable phases within the studied pressure range. The DMC Gibbs free-energy calculations predict that the room temperature $Pbca$ to $P{2}_1/c$ phase transition occurs at 2.1(1) GPa. This prediction is consistent with available experimental results at room temperature. Our DMC calculations show an estimate of 50.6$\pm$0.5 kJ/mol for crystalline benzene lattice energy.

References in corpus (15)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• A Higher-Accuracy van der Waals Density Functional
• Nonlocal van der Waals density functional: The simpler the better
• Perspective: Advances and challenges in treating van der Waals dispersion forces in density functional theory
• Continuum variational and diffusion quantum Monte Carlo calculations
• Smooth relativistic Hartree-Fock pseudopotentials for H to Ba and Lu to Hg
• Norm-conserving Hartree-Fock pseudopotentials and their asymptotic behavior
• Dissociation of high-pressure solid molecular hydrogen: Quantum Monte Carlo and anharmonic vibrational study
• Resonating valence bond wave function with molecular orbitals: Application to first-row molecules
• Energies of the first row atoms from quantum Monte Carlo
• Dissociation energy of the water dimer from Quantum Monte Carlo calculations
• Water on BN doped benzene: A hard test for exchange-correlation functionals and the impact of exact exchange on weak binding
• Spectroscopic data for the LiH molecule from pseudopotential quantum Monte Carlo calculations

Cited by in corpus (1)

• Nature of the Metallization Transition in Solid Hydrogen