The challenges in designing future head disk interface (HDI) demand efficient theoretical modeling tools with flexibility in investigating various combinations of perfluoropolyether (PFPE) and carbon overcoat (COC) materials. For broad range of time and length scales, we developed multiscale/multiphysical modeling approach, which can bring paradigm-shifting improvements in advanced HDI design. In this paper, we introduce our multiscale modeling methodology with an effective strategic framework for the HDI system. Our multiscale methodology in this paper adopts a bottom to top approach beginning with the high-resolution modeling, which describes the intramolecular/intermolecular PFPE-COC degrees of freedom governing the functional oligomeric molecular conformations on the carbon surfaces. By introducing methodology for integrating atomistic/molecular/mesoscale levels via coarse-graining procedures, we investigated static and dynamic properties of PFPE-COC combinations with various molecular architectures. By bridging the atomistic and molecular scales, we are able to systematically incorporate first-principle physics into molecular models, thereby demonstrating a pathway for designing materials based on molecular architecture. We also discussed future materials (e.g., graphene for COC, star-like PFPEs) and systems (e.g., heat-assisted magnetic recording (HAMR)) with higher scale modeling methodology, which enables the incorporation of molecular/mesoscale information into the continuum scale models. 1. Introduction The continuous increase in the areal recording density specification beyond 1？Tb/in2 has led to ever decreasing head media spacing (HMS) requirements at the head disk interface (HDI). The key material components of the HDI are the carbon overcoat (COC) and lubricant layers, which protect the magnetic media from corrosion and tribological damage. Perfluoropolyethers (PFPE) with both functional and nonfunctional groups are standard HDI lubricants due to their low vapor pressure and low surface tension as well as good chemical and thermal stability. To make a more reliable product, improved lubricant and COC materials must have self-healing capability and lubricant-COC adhesion in addition to molecularly thin spreading layer thickness. The challenges involved in designing improved HDI materials require efficient theoretical modeling tools which allow flexibility in investigating various pairs of PFPE-COC materials. Due to the broad range of time and length scales of interest in the HDI components, a multiscale/multi-physical modeling approach can
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