ITR-(ASE)-(sim): Ab Initio Modeling of Self-Assembled Pattern Growth in Heteroepitaxial Alloy Films with Long-Range Elastic interactions

该奖项是根据在信息技术研究征集NSF-04-012项下提交给材料研究部的一份提案而颁发的。该奖项所涵盖的研究活动属于国家重点领域“科学与工程进展”和技术重点领域“计算建模或研究中的模拟创新”。该奖项支持计算研究和教育，以开发模拟算法，旨在研究可用于纳米结构定向自组装的合金薄膜中的图案形成。在几种由不相容物种组成的表面合金膜中，观察到了二维(2D)纳米图案(条纹和圆盘)的自发形成。这些系统在长度尺度上显示出目前即使是最先进的光刻技术也无法达到的常规特征，显示出在纳米级设备的定向自组装中用作掩膜的前景。利用计算机模拟，PI将研究在生长的超薄合金薄膜中条带和圆盘的规则阵列的形成。PI的研究目标是在以下关键方向上取得重大的科学进展：1.识别具有强烈能量倾向的新的合金/衬底系统，形成可用作定向自组装掩膜的长周期有序图案。建立了外延生长超薄膜的模型，可以预测最佳参数，以实现健壮和高度规则的图形。开发用于模拟具有远程弹性相互作用的表面系统的高效计算算法。PI将使用一系列计算研究工具，从从头算电子结构计算到具有远程弹性相互作用的基于格子的动力学蒙特卡罗(KMC)模拟。一个目标是建立超薄异质外延表面合金膜图案形成的热力学和动力学的定量模型。热力学模型将被用来系统地寻找表现出能量趋势的合金系统，以形成具有纳米级周期的图案。除了纯理论上的兴趣外，识别这类系统也有很大的实际需要，因为只有少数已知的图案形成表面合金可以形成定向自组装所需的大规模无缺陷结构。动力学生长模拟可能有助于我们控制生长阶段的结构缺陷数量。这些模型将被用来预测最佳的实验条件，如组成、温度和沉积速度。最后，长程弹性应变效应将用重整化群理论中熟悉的精确粗粒化方法来处理。理论研究将与桑迪亚国家实验室进行的金属表面合金的实验研究合作进行。这一奖项的教育影响更广泛。它包括让本科生和研究生参与在材料研究中使用模拟的计算项目，并为研究代码开发基于HTML和Perl的Web界面，并将它们用于相变和表面生长的热力学和动力学教学。Perl脚本将用于从Web表单收集输入参数，在远程Linux服务器上启动模拟，并在动态生成的Web页面上显示结果。这种方法代表着一个很有前途的未来平台，可以将现有的研究代码与教育活动相结合。获得的经验和Web脚本将免费与社区共享。%该奖项是根据提交给信息技术研究征集NSF-04-012下的材料研究部的提案而颁发的。该奖项所涵盖的研究活动属于国家重点领域“科学与工程进展”和技术重点领域“计算建模或研究中的模拟创新”。该奖项支持计算研究和教育，以开发模拟算法，旨在研究合金薄膜中的图案形成，该图案可以用作在纳米尺度上组装材料和纳米结构的模板。在几种由不相容物种组成的表面合金膜中，观察到了二维(2D)纳米图案(条纹和圆盘)的自发形成。这些系统在长度尺度上显示出目前即使是最先进的光刻技术也无法达到的常规特征，显示出在纳米级设备的定向自组装中用作掩膜的前景。利用计算机模拟，PI将研究在生长的超薄合金薄膜中条带和圆盘的规则阵列的形成。除了纯粹的理论兴趣之外，识别这样的系统还有很大的实际需要，因为只有少数已知的图案形成表面合金可以形成定向自组装所需的大规模无缺陷结构。动力学生长模拟还可以帮助我们控制材料和纳米结构生长过程中的结构缺陷数量。结构缺陷会影响材料和纳米结构的性能。理论研究将与桑迪亚国家实验室进行的金属表面合金的实验研究合作进行。这一奖项的教育影响更广泛。它包括让本科生和研究生参与在材料研究中使用模拟的计算项目，使研究代码更易于使用，并在相变和表面生长的热力学和动力学教学中使用它们。获得的经验和Web脚本将与社区免费分享。*

This award was made on a proposal submitted to the Division of Materials Research under the Information Technology Research solicitation NSF-04-012. Research activities covered by this award fall under the National Priority Area, "Advances in Science and Engineering," and the Technical Focus Area, "Innovation in Computational Modeling or Simulation in Research." This award supports computational research and education to develop simulation algorithms with an aim to study pattern formation in alloy films that could be used for directed self-assembly of nanostructures. Spontaneous formation of two-dimensional (2D) nanoscale patterns (stripes and disks) has been observed in several surface alloy films composed of immiscible species. These systems exhibit regular features on length scales that are currently inaccessible to even the most advanced lithographic techniques, showing promise as masks for use in directed self-assembly of nanoscale devices. Using computer simulations, the PI will study the formation of regular arrays of stripes and disks in growing ultrathin alloy films. The PI's research aims to make significant scientific advances in the following key directions:1. Identification of new alloy/substrate systems with strong energetic tendencies to form long-period ordered patterns, which could be used as masks for directed self-assembly.2. Develop models of epitaxial growth of ultrathin films that can predict optimal parameters for achieving robust and highly regular patterning.3. Develop efficient computational algorithms for simulating surface systems with long-range elastic interactions.The PI will use a range of computational research tools spanning ab initio electronic structure calculations to lattice-based Kinetic Monte Carlo (KMC) simulations with long-ranged elastic interactions. A goal is to construct quantitative models of the thermodynamics and kinetics of pattern formation in ultrathin heteroepitaxial surface alloy films. Thermodynamic models will be used to systematically search for alloy systems that exhibit energetic tendencies to form patterns with nanometer-scale periodicities. Besides pure theoretical interest, there is a strong practical need to identify such systems as there are only a few known cases of pattern-forming surface alloys that can form large-scale defect-free structures required for directed self-assembly.Kinetic growth simulations may help us to control the number of structural defects during the growth stage. These models will be used to predict optimum experimental conditions such as the composition, temperature, and deposition rate. Finally, long-range elastic strain effects will be treated by accurate coarse-graining methods familiar from renormalization group theory. Theoretical research will be performed in collaboration with experimental studies of metallic surface alloys carried out at Sandia National Labs.Education is a broader impact of this award. It includes involving undergraduate and graduate students in computational projects on the use of simulation in materials research and developing an HTML- and Perl-based Web interface for research codes and use them in teaching thermodynamics and kinetics of phase transformations and surface growth. Perl scripts will be used to collect input parameters from a Web form, launch the simulation on a remote LINUX server, and display the results on dynamically generated Web pages. This approach represents a promising future platform for integrating existing research codes with educational activities. The acquired experience and Web scripts will be freely shared with the community.%%%This award was made on a proposal submitted to the Division of Materials Research under the Information Technology Research solicitation NSF-04-012. Research activities covered by this award fall under the National Priority Area, "Advances in Science and Engineering," and the Technical Focus Area, "Innovation in Computational Modeling or Simulation in Research." This award supports computational research and education to develop simulation algorithms with an aim to study pattern formation in alloy films that could be used as a template to assemble materials and nanostructures on the nanoscale. Spontaneous formation of two-dimensional (2D) nanoscale patterns (stripes and disks) has been observed in several surface alloy films composed of immiscible species. These systems exhibit regular features on length scales that are currently inaccessible to even the most advanced lithographic techniques, showing promise as masks for use in directed self-assembly of nanoscale devices. Using computer simulations, the PI will study the formation of regular arrays of stripes and disks in growing ultrathin alloy films. Besides pure theoretical interest, there is a strong practical need to identify such systems as there are only a few known cases of pattern-forming surface alloys that can form large-scale defect-free structures required for directed self-assembly. Kinetic growth simulations may also help us to control the number of structural defects during the growth of materials and nanosctructures. Structural defects affect the properties of materials and nanstructures. Theoretical research will be performed in collaboration with experimental studies of metallic surface alloys carried out at Sandia National Labs.Education is a broader impact of this award. It includes involving undergraduate and graduate students in computational projects on the use of simulation in materials research and making research codes more "user friendly" and using them in teaching thermodynamics and kinetics of phase transformations and surface growth. The acquired experience and Web scripts will be freely shared with the community.***